input validation in asp.net cannot work - asp.net

Question

I'm facing a problem in validation. I have done validation checking before user submit the button. Buy why the registration still can be added into database. Previously this page worked perfectly just after combining other pages with my team mate it cannot work :(
This is my Registration.aspx :
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
<table width="100%" cellspacing="0" cellpadding="0" border="0">
<tr>
<td width="30%" valign="top">
<table width="100%">
<tr>
<td class="TableTitle">
Member Registration
</td>
</tr>
<tr>
<td>
<p>
Please enter your account information.</p>
<asp:ValidationSummary ID="RegUserValidationSummary" runat="server" CssClass="validation"
ValidationGroup="RegUserValidationGroup" />
</td>
</tr>
<tr>
<td class="PageContent">
<div>
<fieldset>
<legend>Account Information</legend>
<table width="100%">
<tr>
<td width="35%">
<asp:Label ID="lblUserName" runat="server" AssociatedControlID="txtUserName">Username:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtUserName" runat="server" CssClass="textEntry" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="UserNameRequired" runat="server" ControlToValidate="txtUserName"
CssClass="failureNotification" ErrorMessage="User Name is required." ToolTip="User Name is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblPassword" runat="server" AssociatedControlID="txtPassword">Password:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtPassword" runat="server" CssClass="passwordEntry" TextMode="Password"
Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="PasswordRequired" runat="server" ControlToValidate="txtPassword"
CssClass="failureNotification" ErrorMessage="Password is required." ToolTip="Password is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblConfirmPassword" runat="server" AssociatedControlID="txtConfirmPassword">Confirm Password:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtConfirmPassword" runat="server" CssClass="passwordEntry" TextMode="Password"
Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="ConfirmPasswordRequired" runat="server" ControlToValidate="txtConfirmPassword"
CssClass="failureNotification" Display="Dynamic" ErrorMessage="Confirm Password is required."
ToolTip="Confirm Password is required." ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
<asp:CompareValidator ID="PasswordCompare" runat="server" ControlToCompare="txtPassword"
ControlToValidate="txtConfirmPassword" CssClass="failureNotification" Display="Dynamic"
ErrorMessage="The Confirm Password must match the Password entry." ValidationGroup="RegUserValidationGroup">*</asp:CompareValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblSecQuestion1" runat="server" AssociatedControlID="ddlSecQuestion">Security Question:</asp:Label>
</td>
<td>
<asp:DropDownList ID="ddlSecQuestion" runat="server" Width="250px">
<asp:ListItem>Where were you when you had your first kiss? </asp:ListItem>
<asp:ListItem>What was your dream job as a child? </asp:ListItem>
<asp:ListItem>What is the first name of the boy or girl that you first kissed?</asp:ListItem>
<asp:ListItem Value="•What is the middle name of your youngest child?">What is the middle name of your youngest child?</asp:ListItem>
<asp:ListItem>What is the name of your favourite pet?</asp:ListItem>
<asp:ListItem>In what city or town did your mother and father meet?</asp:ListItem>
<asp:ListItem>In what city or town was your first job?</asp:ListItem>
</asp:DropDownList>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblSecAns" runat="server" AssociatedControlID="TxtSecAns">Security Answer:</asp:Label>
</td>
<td>
<asp:TextBox ID="TxtSecAns" runat="server" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="SecAnsRequired" runat="server" ControlToValidate="TxtSecAns"
CssClass="failureNotification" ErrorMessage="Security Answer is required." ToolTip="Security Answer is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
</table>
</fieldset>
<fieldset>
<legend>Personal Information</legend>
<table width="100%">
<tr>
<td width="35%">
<asp:Label ID="lblName" runat="server" AssociatedControlID="txtName">Name:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtName" runat="server" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtName"
CssClass="failureNotification" ErrorMessage="Name is required." ToolTip="Name is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblICNumber" runat="server" AssociatedControlID="txtICNumber">IC Number:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtICNumber" runat="server" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="txtICNumber"
CssClass="failureNotification" ErrorMessage="IC Number is required." ToolTip="IC Number is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ControlToValidate="txtICNumber"
CssClass="failureNotification" ErrorMessage="Invalid Format of IC Number." ValidationExpression="\d{6}-\d{2}-\d{4}"
ValidationGroup="RegUserValidationGroup">*</asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblEmail" runat="server" AssociatedControlID="txtEmail">Email:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtEmail" runat="server" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator3" runat="server" ControlToValidate="txtEmail"
CssClass="failureNotification" ErrorMessage="Email is required." ToolTip="Email is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
<asp:RegularExpressionValidator ID="RegularExpressionValidator2" runat="server" ControlToValidate="txtEmail"
CssClass="failureNotification" ErrorMessage="Invalid Format of Email." ValidationExpression="\w+([-+.']\w+)*#\w+([-.]\w+)*\.\w+([-.]\w+)*"
ValidationGroup="RegUserValidationGroup">*</asp:RegularExpressionValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblContactNumber" runat="server" AssociatedControlID="txtContactNumber">Contact Number:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtContactNumber" runat="server" Width="130px"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator4" runat="server" ControlToValidate="txtContactNumber"
CssClass="failureNotification" ErrorMessage="Contact Number is required." ToolTip="Contact Number is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
<tr>
<td>
<asp:Label ID="lblAddress" runat="server" AssociatedControlID="txtAddress">Address:</asp:Label>
</td>
<td>
<asp:TextBox ID="txtAddress" runat="server" Width="160px" Height="60px" TextMode="MultiLine"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator5" runat="server" ControlToValidate="txtAddress"
CssClass="failureNotification" ErrorMessage="Address is required." ToolTip="Address is required."
ValidationGroup="RegUserValidationGroup">*</asp:RequiredFieldValidator>
</td>
</tr>
</table>
</fieldset>
<p class="submitButton">
<asp:ImageButton ID="bthSubmit" runat="server" CommandName="Submit" ImageUrl="~/Forms/image/Button/Submit1.png"
ValidationGroup="RegUserValidationGroup" />
<asp:ImageButton ID="btnCancel" runat="server" CausesValidation="False" CommandName="Cancel"
ImageUrl="~/Forms/image/Button/cancel.png" />
</p>
</div>
</td>
</tr>
</table>
</td>
</tr>
</table>
</asp:Content>
Here is my Registration.aspx.vb :
Imports System.Data.Common
Partial Class Forms_Account_Registration
Inherits System.Web.UI.Page
Private memberObj As New MemberObj
Private memberManager As New MemberManager
Protected Sub bthSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles bthSubmit.Click
Dim oCommand As DbCommand = DbManager.GetCommandSP
Dim encryptor As New Encryption.Encryptor
Dim isDuplicateUser As Boolean
Dim isDuplicateIC As Boolean
Try
If memberManager.CheckDuplicateUser(oCommand, (txtUserName.Text.Trim).ToLower) = False Then
isDuplicateUser = False
Else
isDuplicateUser = True
End If
If isDuplicateUser = False Then
If memberManager.CheckDuplicateUserIC(oCommand, (txtICNumber.Text.Trim)) = False Then
isDuplicateIC = False
Else
isDuplicateIC = True
lblErrorMsg.Text = "Sorry,This IC number has been registered. An IC number can use to create ONE account only."
myDiv.Visible = True
End If
Else
isDuplicateIC = True
lblErrorMsg.Text = "Sorry, this username is already in use. Please choose other username."
myDiv.Visible = True
End If
Catch ex As Exception
Manager.LogManager.WriteLine(ex)
Response.Redirect("../500 Internal Server Error.aspx")
End Try
If isDuplicateIC = False Then
memberObj.UserName = txtUserName.Text.Trim.ToLower
memberObj.Password = encryptor.Encrypt(txtPassword.Text.Trim)
memberObj.SecurityQuestion = ddlSecQuestion.SelectedValue
memberObj.SecurityAnswer = TxtSecAns.Text
memberObj.MemberName = txtName.Text
memberObj.MemberIC = txtICNumber.Text
memberObj.MemberEmail = txtEmail.Text
memberObj.ContactNo = txtContactNumber.Text
memberObj.MemberAddress = txtAddress.Text
memberObj.MemberStatus = "UNBLOCK"
memberObj.isAllowedForum = "Y"
memberObj.CreatedDate = Today.Date
memberManager.Insert(oCommand, memberObj)
lblErrorMsg.Text = ""
myDiv.Visible = False
lblSuccessMsg.Text = "You have been successfully registered."
myDivSuccess.Visible = True
End If
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not Page.IsPostBack Then
lblErrorMsg.Text = ""
myDiv.Visible = False
lblSuccessMsg.Text = ""
myDivSuccess.Visible = False
End If
End Sub
End Class