I've suprisingly not been able to find examples on this.  I'm creating
a user account setup page, and the validators work fine on all the
other fields.   But now I'm creating a customvalidator (for the first
time) and it is not doing anything.  The page needs to see if a
username already exists.  Am I doing this right?

<asp:textbox TabIndex="1" ID="tLogin" MaxLength="40" runat="server" />
<asp:customvalidator id="Customvalidator1" runat="server"
EnableClientScript="False" Font-Bold="True" ErrorMessage="Username
already exists." ControlToValidate="tLogin"
OnServerValidate="CheckUser" Display="Dynamic"/>

   void CheckUser(object source,
System.Web.UI.WebControls.ServerValidateEventArgs args)
   {
       TextBox b;
       b = fLogin.FindControl("tLogin") as TextBox;
       String lg = b.Text;
       String strConn = "PROVIDER=Microsoft.Jet.OLEDB.4.0;DATA
SOURCE=" + Server.MapPath("info.mdb") + ";";
       OleDbConnection Conn = new OleDbConnection(strConn);
       Conn.Open();
       String strSQL = "SELECT * FROM Customers WHERE Login = '" + lg
+ "'";
       OleDbCommand Cmd = new OleDbCommand(strSQL, Conn);
       OleDbDataReader Dr =
Cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection);
       if (Dr.HasRows)
       {
           args.IsValid = false;
       } else args.IsValid = true;
       Conn.Close();
   }