custom validator is not firing on the server side code

Question

Hi Friends,

 

working on the cusom validator in aspx page and validation method from the server side writen but it not firing the method

 

aspx page

<td style="width: 25%; height: 21px" rowspan="1" colspan="1" style="border-collapse: collapse" class="br-td3">
<asp:TextBox ID="txtName" runat="server" MaxLength="30"></asp:TextBox>
<asp:CustomValidator ID="valName" runat="server"><img src="images/error.gif" /></asp:CustomValidator>
<asp:CustomValidator ID="valNamen" runat="server" Display="Dynamic" ForeColor="Red" ErrorMessage="" OnServerValidate="valNamen_ServerValidate"></asp:CustomValidator>
</td>

 

and in the server side written the code like this

protected void valNamen_ServerValidate(object source, ServerValidateEventArgs args)
{

if (txtName.Text == string.Empty)
{
valNamen.ErrorMessage = "Please enter Valid Name.";
args.IsValid = false;
}

}

 

but th method is not firing any time.

 

let us know if any thing i am missing here