<com:TContent ID="main" > Username: <com:TTextBox ID="Username" /> <com:TRequiredFieldValidator ControlToValidate="Username" Text="Username is required." Display="Dynamic"/> <br/> Password: <com:TTextBox ID="Password" TextMode="Password" /><br/> <com:TButton Text="Login" /> <com:TCustomValidator ControlToValidate="Password" Text="Login failed." Display="Dynamic" OnServerValidate="login" /> <com:TLabel ID="Error" /> </com:TContent>