Validate non-required fields.

I have been playing around with the CreateUser Wizard these past few days and have modified the template successfully, but I've run into a snag. Along with the standard wizard fields I have added 5 custom fields: Title, FName, MidInit, LName, & Suffix. I validate the FName & LName as required fields and that works fine.
asp:RequiredFieldValidator The Title, MidInit & Suffix are not required fields and tried to validate them with the asp BaseValidator:
<td> <asp:TextBox ID="txtMidInit" runat="server" MaxLength="1"></asp:TextBox> <asp:BaseValidator ControlToValidate="txtMidInit" /> </td> But I get an error by the IDE with a green squiggly line saying the BaseValidator is not a known element. FYI - this is the exact same place I would put the asp:RequiredfieldValidator which is ...