<%@ Page Language="C#" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server"> <title>Validation Image</title> </head> <body> <form id="form1" runat="server"> <div> <asp:Label id="lblFirstName" Text="First Name" AssociatedControlID="txtFirstName" Runat="server" /> <br /> <asp:TextBox id="txtFirstName" Runat="server" /> <asp:RequiredFieldValidator id="reqFirstName" ControlToValidate="txtFirstName" Text="<img src='Error.gif' alt='First name is required.' />" Runat="server" /> <br /><br /> <asp:Button id="btnSubmit" Text="Submit" Runat="server" /> </div> </form> </body> </html>