panel is not working on dropdown click - asp.net

Question

This is mydesign part. i am showing panels on dropdwon click but its not working.
i have others tab too in tab container.
<ContentTemplate>
<h3 class="headr">Please Select a Category From Following</h3>
<div class="dropdown">
<asp:Image ID="culD" runat="server" Height="200px" Width="200px" class="dropbtn" ImageUrl="~/User/assets/Images/Explore/c_banner.jpg"></asp:Image>
<div class="dropdown-content">
<asp:DropDownList ID="cult" Class="cultr" runat="server" OnSelectedIndexChanged="cult_SelectedIndexChanged" Width="200px" AutoPostBack="True">
<asp:ListItem>Select</asp:ListItem>
<asp:ListItem Value="D">Dance</asp:ListItem>
<asp:ListItem Value="S">Singing</asp:ListItem>
<asp:ListItem Value="o">other</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<div class="dropdown">
<asp:Image ID="sport" runat="server" Height="200px" Width="200px" class="dropbtn" ImageUrl="~/User/assets/Images/Explore/s_banner.jpg" />
<div class="dropdown-content">
<asp:DropDownList ID="sportsD" Class="cultr" runat="server" OnSelectedIndexChanged="sportsD_SelectedIndexChanged" Width="200px" AutoPostBack="True">
<asp:ListItem>Select</asp:ListItem>
<asp:ListItem Value="CR">Cricket</asp:ListItem>
<asp:ListItem Value="C">Chess</asp:ListItem>
<asp:ListItem Value="CRM">Carrom</asp:ListItem>
</asp:DropDownList>
</div>
</div>
<asp:UpdatePanel runat="server" ID="dc">
<contenttemplate>
<asp:Panel runat="server" ID="dan" class="npan" Width="900px" Height="500px">
<h3 style="text-align: center" class="panhed">Please Fill This Form TO Participate(Dance Registration)</h3>
<div id="snam" runat="server" class="nam">
<asp:Label ID="Label1" runat="server" Text="Name of participant:"></asp:Label>
<asp:TextBox ID="TextBox1" CssClass="txtcls" runat="server" TextMode="MultiLine"></asp:TextBox>
<asp:Button ID="addm" class="addbtn" runat="server" autopostback="true" Text="Add member" OnClick="addm_Click" />
</div>
<div id="Div3" runat="server" class="nams">
<asp:Label ID="Label3" runat="server" autopostback="true" Text="Name of 2nd participant:"></asp:Label>
<asp:TextBox ID="TextBox2" CssClass="txtscls" runat="server"></asp:TextBox>
</div>
<div id="Div29" runat="server" class="nams">
<asp:Label ID="Label27" runat="server" Text="Age:"></asp:Label>
<asp:TextBox ID="TextBox22" CssClass="agtxt" placeholder="1st" runat="server"></asp:TextBox><asp:TextBox ID="TextBox24" CssClass="agstxt" placeholder="2nd" AutoPostBack="true" runat="server"></asp:TextBox>
</div>
<div id="Div2" runat="server" class="cate">
<asp:Label ID="Label2" runat="server" Text="Select Category:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList1" Class="drpd" OnSelectedIndexChanged="DropDownList1_SelectedIndexChanged">
<asp:ListItem Value="22">select</asp:ListItem>
<asp:ListItem Value="Ss">Solo</asp:ListItem>
<asp:ListItem Value="Dd">Duet</asp:ListItem>
<asp:ListItem Value="Gg">Group</asp:ListItem>
</asp:DropDownList>
</div>
<div id="divv" class="mobn" runat="server">
<asp:Label ID="Label5" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="TextBox4" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Div6" runat="server" class="eml">
<asp:Label ID="Label6" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="TextBox5" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="Div7" runat="server" class="yer">
<asp:Label ID="Label7" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList2" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div8" runat="server" class="btndiv">
<asp:Button ID="Button1" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
</contenttemplate>
</asp:UpdatePanel>
<asp:Panel ID="singinp" runat="server" class="npan" Width="800px" Height="700px">
<h3 class="panhed">Please Fill This Form TO Participate(Singing Registration)</h3>
<div id="namep" runat="server" class="nam">
<asp:Label ID="name" runat="server" Text="Name of participant:"></asp:Label>
<asp:TextBox ID="txtname" CssClass="txtcls" TextMode="MultiLine" runat="server"></asp:TextBox>
<asp:Button ID="Button6" class="addbtn" runat="server" autopostback="true" Text="Add member" OnClick="Button6_Click" />
</div>
<div id="namesp" runat="server" class="nams" autopostback="true">
<asp:Label ID="scndname" runat="server" autopostback="true" Text="Name of 2nd participant:"></asp:Label>
<asp:TextBox ID="Txtnames" CssClass="txtscls" AutoPostBack="True" runat="server"></asp:TextBox>
</div>
<div id="Div31" runat="server" class="nams">
<asp:Label ID="Label29" runat="server" Text="Age:"></asp:Label>
<asp:TextBox ID="TextBox25" CssClass="agtxt" placeholder="1st" runat="server"></asp:TextBox><asp:TextBox ID="TextBox26" CssClass="agstxt" placeholder="2nd" AutoPostBack="True" runat="server"></asp:TextBox>
</div>
<div id="cat" runat="server" class="cate">
<asp:Label ID="type" runat="server" Text="Select Category:"></asp:Label>
<asp:DropDownList runat="server" ID="dcat" Class="drpd" Style="width: auto;" OnSelectedIndexChanged="dcat_SelectedIndexChanged">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem Value="1">Solo singing</asp:ListItem>
<asp:ListItem Value="2">Duet singing</asp:ListItem>
<asp:ListItem Value="3">Group singing</asp:ListItem>
</asp:DropDownList>
</div>
<div id="clgn" runat="server" class="clgname">
<asp:Label ID="cname" runat="server" Text="Name of College:"></asp:Label>
<asp:TextBox ID="cnamet" CssClass="clgtxt" runat="server"></asp:TextBox>
</div>
<div id="mob" runat="server" class="mobn">
<asp:Label ID="mobi" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="Imob" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Email" runat="server" class="eml">
<asp:Label ID="emal" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="emao" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="ydrp" runat="server" class="yer">
<asp:Label ID="yr" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="yers" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="submit" runat="server" class="btndiv">
<asp:Button ID="btn" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
<asp:Panel ID="other" runat="server" Class="npan" Width="800px" Height="700px">
<h3 style="text-align: center" class="panhed">Please Fill This Form TO Participate(Other Event Registration)</h3>
<div id="Div1" runat="server" class="nam">
<asp:Label ID="Label8" runat="server" Textmode="MultiLine" Text="Name of participant/s:"></asp:Label>
<asp:TextBox ID="TextBox6" CssClass="txtc" runat="server"></asp:TextBox>
</div>
<div id="Div9" runat="server" class="cate">
<asp:Label ID="Label9" runat="server" Text="Select Category:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList3" Class="drpd">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>Solo </asp:ListItem>
<asp:ListItem>Duet </asp:ListItem>
<asp:ListItem>Group</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div10" runat="server" class="nams">
<asp:Label ID="Label10" runat="server" Text="Specify Event Name:"></asp:Label>
<asp:TextBox ID="TextBox7" CssClass="txtcs" runat="server" Placeholder="Ex-Drama/Fashion Show"></asp:TextBox>
</div>
<div id="Div11" runat="server" class="clgname">
<asp:Label ID="Label11" runat="server" Text="Name of College:"></asp:Label>
<asp:TextBox ID="TextBox8" CssClass="clgtxt" runat="server"></asp:TextBox>
</div>
<div id="Div12" runat="server" class="mobn">
<asp:Label ID="Label12" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="TextBox9" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Div13" runat="server" class="eml">
<asp:Label ID="Label13" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="TextBox10" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="Div14" runat="server" class="yer">
<asp:Label ID="Label14" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList4" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div15" runat="server" class="btndiv">
<asp:Button ID="Button2" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
<asp:Panel ID="chess" runat="server" Class="npan" Width="800px" Height="700px">
<h3 style="text-align: center" class="panhed">Please Fill This Form TO Participate(Chess Registration)</h3>
<div id="Div4" runat="server" class="nam">
<asp:Label ID="Label4" runat="server" Text="Name of participant/s:"></asp:Label>
<asp:TextBox ID="TextBox3" CssClass="txtc" runat="server"></asp:TextBox>
</div>
<div id="Div16" runat="server" class="nams">
<asp:Label ID="Label16" runat="server" Text="Age:"></asp:Label>
<asp:TextBox ID="TextBox11" CssClass="agtxt" runat="server"></asp:TextBox>
</div>
<div id="Div17" runat="server" class="clgname">
<asp:Label ID="Label17" runat="server" Text="Name of College:"></asp:Label>
<asp:TextBox ID="TextBox12" CssClass="clgtxt" runat="server"></asp:TextBox>
</div>
<div id="Div18" runat="server" class="mobn">
<asp:Label ID="Label18" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="TextBox13" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Div19" runat="server" class="eml">
<asp:Label ID="Label19" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="TextBox14" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="Div20" runat="server" class="yer">
<asp:Label ID="Label20" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList6" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div21" runat="server" class="btndiv">
<asp:Button ID="Button3" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
<asp:UpdatePanel ID="carup" runat="server">
<ContentTemplate>
<asp:Panel ID="carrom" runat="server" Class="npan" Width="800px" Height="700px">
<h3 style="text-align: center" class="panhed">Please Fill This Form TO Participate(Carrom Registration)</h3>
<div id="Div5" runat="server" class="nam">
<asp:Label ID="Label15" runat="server" Text="Name of participant:"></asp:Label>
<asp:TextBox ID="TextBox15" CssClass="txtcls" runat="server"></asp:TextBox>
<asp:Button ID="Button5" class="addbtn" runat="server" Text="Add member" Autopostback="true" OnClick="Button5_Click" />
</div>
<div id="Div28" runat="server" class="nams">
<asp:Label ID="Label26" runat="server" autopostback="true" Text="Name of 2nd participant:"></asp:Label>
<asp:TextBox ID="TextBox20" CssClass="txtscls" runat="server"></asp:TextBox>
</div>
<div id="Div22" runat="server" class="nams">
<asp:Label ID="Label21" runat="server" autopostback="true" Text="Age:"></asp:Label>
<asp:TextBox ID="TextBox16" CssClass="agtxt" placeholder="1st" runat="server"></asp:TextBox>
<asp:TextBox ID="TextBox21" CssClass="agstxt" placeholder="2nd" AutoPostBack="true" runat="server"></asp:TextBox>
</div>
<div id="Div23" runat="server" class="clgname">
<asp:Label ID="Label22" runat="server" Text="Name of College:"></asp:Label>
<asp:TextBox ID="TextBox17" CssClass="clgtxt" runat="server"></asp:TextBox>
</div>
<div id="Div24" runat="server" class="mobn">
<asp:Label ID="Label23" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="TextBox18" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Div25" runat="server" class="eml">
<asp:Label ID="Label24" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="TextBox19" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="Div26" runat="server" class="yer">
<asp:Label ID="Label25" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList5" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div27" runat="server" class="btndiv">
<asp:Button ID="Button4" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
</ContentTemplate>
</asp:UpdatePanel>
<asp:Panel ID="cricket" runat="server" Class="npan" Width="800px" Height="700px">
<h3 style="text-align: center" class="panhed">Please Fill This Form TO Participate(Cricket Registration)</h3>
<div id="Div30" runat="server" class="nam">
<asp:Label ID="Label28" runat="server" Text="Name of participant/s:"></asp:Label>
<asp:TextBox ID="TextBox23" CssClass="txtcr" TextMode="MultiLine" runat="server"></asp:TextBox>
</div>
<div id="Div37" runat="server" class="clgname">
<asp:Label ID="Label34" runat="server" Text="Name of College:"></asp:Label>
<asp:TextBox ID="TextBox28" CssClass="clgtxt" runat="server"></asp:TextBox>
</div>
<div id="Div38" runat="server" class="mobn">
<asp:Label ID="Label35" runat="server" Text="Mobile No:"></asp:Label>
<asp:TextBox ID="TextBox29" CssClass="mobtxt" runat="server"></asp:TextBox>
</div>
<div id="Div39" runat="server" class="eml">
<asp:Label ID="Label36" runat="server" Text="E-Mail:"></asp:Label>
<asp:TextBox ID="TextBox30" CssClass="emtxt" runat="server"></asp:TextBox>
</div>
<div id="Div40" runat="server" class="yer">
<asp:Label ID="Label37" runat="server" Text="Select Year:"></asp:Label>
<asp:DropDownList runat="server" ID="DropDownList8" Class="drpds">
<asp:ListItem>select</asp:ListItem>
<asp:ListItem>First</asp:ListItem>
<asp:ListItem>Second</asp:ListItem>
<asp:ListItem>Third</asp:ListItem>
<asp:ListItem>other</asp:ListItem>
</asp:DropDownList>
</div>
<div id="Div41" runat="server" class="btndiv">
<asp:Button ID="Button7" runat="server" Class="Btncss" Text="Submit" />
</div>
</asp:Panel>
</asp:UpdatePanel>
</ContentTemplate>
my codebehind
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
public partial class User_Default : System.Web.UI.Page
{
SqlConnection con = new SqlConnection(#"Data Source=ADMIN-PC\SQLEXPRESS;Initial Catalog=festopedia;Integrated Security=True");
int FID;
protected void Page_Load(object sender, EventArgs e)
{
showclg();
dan.Visible = false;
other.Visible = false;
singinp.Visible = false;
chess.Visible = false;
cricket.Visible = false;
carrom.Visible = false;
}
public void showclg()
{
if (Request.QueryString["FID"].ToString() == null)
{
Response.Redirect("Explore_Event.aspx");
}
else
{
FID = Convert.ToInt32(Request.QueryString["FID"].ToString());
con.Open();
SqlCommand cmd = con.CreateCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "Select * from FESTDETAILS where FID='" + FID + "'";
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(dt);
festexprepeater.DataSource = dt;
festexprepeater.DataBind();
con.Close();
}
}
public void Showevent()
{
}
protected void singb_Click1(object sender, EventArgs e)
{
singinp.Visible = true;
dan.Visible = false;
}
protected void cult_SelectedIndexChanged(object sender, EventArgs e)
{
if (cult.SelectedValue =="D")
{
dan.Visible = true;
singinp.Visible = false;
other.Visible = false;
}
else if (cult.SelectedValue == "S")
{
singinp.Visible = true;
dan.Visible = false;
other.Visible = false;
}
else
{
other.Visible = true;
singinp.Visible = false;
dan.Visible = false;
chess.Visible = false;
}
}
protected void sportsD_SelectedIndexChanged(object sender, EventArgs e)
{
if (sportsD.SelectedValue == "C")
{
dan.Visible = false;
singinp.Visible = false;
other.Visible = false;
chess.Visible = true;
}
else if (sportsD.SelectedValue == "CRM")
{
carrom.Visible = true;
dan.Visible = false;
singinp.Visible = false;
other.Visible = false;
chess.Visible = false;
}
else if (sportsD.SelectedValue == "CR")
{
cricket.Visible = true;
carrom.Visible = false;
dan.Visible = false;
singinp.Visible = false;
other.Visible = false;
chess.Visible = false;
}
}
protected void addm_Click(object sender, EventArgs e)
{
Div3.Visible = true;
dan.Visible = true;
TextBox24.Visible = true;
}
protected void Button5_Click(object sender, EventArgs e)
{
carrom.Visible = true;
TextBox21.Visible = true;
Div28.Visible = true;
}
protected void Button6_Click(object sender, EventArgs e)
{
carrom.Visible = true;
TextBox26.Visible = true;
namesp.Visible = true;
singinp.Visible = true;
}
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropDownList1.SelectedValue == "Dd")
{
addm.Visible = true;
}
if (DropDownList1.SelectedValue == "Gg")
{
TextBox1.TextMode = TextBoxMode.MultiLine;
}
}
protected void TextBox1_TextChanged(object sender, EventArgs e)
{
int charRows = 0;
string tbCOntent;
int chars = 0;
tbCOntent = TextBox1.Text;
TextBox1.Columns = 10;
chars = tbCOntent.Length;
charRows = chars / TextBox1.Columns;
int remaining = chars - charRows * TextBox1.Columns;
if (remaining == 0)
{
TextBox1.Rows = charRows;
TextBox1.TextMode = TextBoxMode.MultiLine;
}
else
{
TextBox1.Rows = charRows + 1;
TextBox1.TextMode = TextBoxMode.MultiLine;
}
}
protected void dcat_SelectedIndexChanged(object sender, EventArgs e)
{
if (dcat.SelectedValue == "2")
{
Button6.Visible = true;
}
}
}
when i am clicking on image drop down panel is not getting visible.