<%@ Page Language="VB" %> <script runat="server"> Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Label1.Text = "Page is valid!" End Sub </script> <html xmlns="http://www.w3.org/1999/xhtml" > <head id="Head1" runat="server"> <title>RequiredFieldValidator</title> </head> <body> <form id="form1" runat="server"> <div> <asp:DropDownList id="DropDownList1" runat="server"> <asp:ListItem Selected="True">Select a profession</asp:ListItem> <asp:ListItem>Programmer</asp:ListItem> <asp:ListItem>Lawyer</asp:ListItem> <asp:ListItem>Doctor</asp:ListItem> <asp:ListItem>Artist</asp:ListItem> </asp:DropDownList> <asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server" ErrorMessage="Please make a selection" ControlToValidate="DropDownList1" InitialValue="Select a profession"> </asp:RequiredFieldValidator> <br /> <asp:Button ID="Button1" Runat="server" Text="Submit" OnClick="Button1_Click" /> <br /> <br /> <asp:Label ID="Label1" Runat="server"></asp:Label> </div> </form> </body> </html>