Hi. I am trying to validate a MaskedTextBox in Asp.net using a RegularExpressionValidator control. The validation works on a normal textbox, but I can't get it to work on the MaskedTextBox. I'm getting the error message Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index
Here is my code:
<telerik:RadMaskedTextBox ID="txtFederalTaxID" runat="server" Mask="##-#######" CssClass="field" SelectionOnFocus="SelectAll"> </telerik:RadMaskedTextBox> <asp:RequiredFieldValidator ID="RequiredFieldValidator28" runat="server" ErrorMessage="*" ControlToValidate="txtFederalTaxID" InitialValue="" ValidationGroup="Terms"></asp:RequiredFieldValidator> <asp:RegularExpressionValidator ID="RegularExpressionValidator1" ControlToValidate="txtFederalTaxID" runat="server" ValidationExpression="^(?!(\d)\1+$|(?:0(?=1)|1(?=2)|2(?=3)|3(?=4)|4(?=5)|5(?=6)|6(?=7)|7(?=8)|8(?=9)|9(?=0)){5}\d$|(?:0(?=9)|1(?=0)|2(?=1)|3(?=2)|4(?=3)|5(?=4)|6(?=5)|7(?=6)|8(?=7)|9(?=8)){5}\d$)\d{9}$" ErrorMessage="Invalid!" Width="20px"></asp:RegularExpressionValidator>