Update paneel blocks execution of some error messages - asp.net

Question

I ave an asp page with 1 update panels with 2 panels which are controlled by 2 buttons if you click in first button first panel appears and second becomes hidden and if you click second button the same thing happens for the second panel. It's working ok and no problem about that.
The problem begins in the second panel where I have another update panel which is in charge of printing error messages. The messages which just check the length of input are working ok, but those messages which involve querying the database to check the validity of id are not being printed .
I thought the querying are the problem and I've tried them in a separated page without update panels and they are working ok. The problem lays somewhere with Update panels. And I really can't understand where. I would be most grateful if you can help me.
This is front end code(i omit some insignificant details):
<asp:Button ID="Button1" runat="server" Text="[Input your Id?]" />
<asp:Button ID="Button2" runat="server" Text="[Aditional info]" />
.....
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
< asp:Panel ID="Panel1" runat="server">
some code here
</asp:Panel>
<asp:Panel ID="Panel2" runat="server">
<b>*ID Number: </b>
<asp:TextBox ID="IdNo" runat="server" ></asp:TextBox><font size='2'>
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" class="errorMess" ErrorMessage="Letters are not Allowed!!" ControlToValidate="IdNumb" ValidationExpression="\d+"
runat="server" />
<asp:UpdatePanel ID="UpdatePanel3" runat="server">
<ContentTemplate>
<asp:Label ID="errorEm" class="errorMess" runat="server" Text="Please fill in the required fields"></asp:Label>
<asp:Label ID="errorLenght" class="errorMess" runat="server" Text="Id is too long!!!"></asp:Label>
<asp:Label ID="errorUser" class="errorMess" runat="server" Text="Id is not valid!!!"></asp:Label>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Button5" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
<asp:Button ID="Button5" runat="server" Text="Generate" /></td></tr>
</asp:Panel>
</ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Button1" EventName="Click" />
</Triggers>
</asp:UpdatePanel>
and this is backend VB code:
Protected Sub Button5_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button5.Click
If IdNo.Text = "" Then
Panel1.Visible = False
Panel2.Visible = True
errorEm.Visible = True
ElseIf IdNo.Text.Length > 9 Then
Panel1.Visible = False
Panel2.Visible = True
errorLenght.Visible = True
Else
Try 'everything that comes here does not work'
myconn.Open()
Dim stquery As String = "SELECT * from account WHERE user_id= #id"
Dim smd = New MySqlCommand(stquery, myconn)
smd.Parameters.AddWithValue("#id", Convert.ToInt32(IdNo.Text))
Dim myreader = smd.ExecuteReader()
If Not myreader.HasRows Then
Panel1.Visible = False
Panel2.Visible = True
errorUser.Visible = True
myconn.Close()
Return
Else
Panel1.Visible = False
Panel2.Visible = True
myreader.Read()
Dim ErrorMessage As String = "alert('User has been found');"
Page.ClientScript.RegisterStartupScript(Me.GetType(), "ErrorAlert", ErrorMessage, True)
myconn.Close()
End If
myconn.Close()
Catch ex As Exception
Dim ErrorMessage As String = "alert('" & ex.Message.ToString() & "');"
Page.ClientScript.RegisterStartupScript(Me.GetType(), "ErrorAlert", ErrorMessage, True)
myconn.Close()
End Try
End If
End Sub

Answer 1

When you want to execute script from inside of Update panel - don't use
Page.ClientScript.RegisterStartupScript
Use
ClientScriptManager.RegisterStartupScript
instead.
Ref: http://msdn.microsoft.com/en-us/library/system.web.ui.clientscriptmanager.registerstartupscript.aspx