asp:MaskedEditExtender stops validator working - asp.net

Question

I have a RequiredFieldValidator. The code is below:
<asp:TextBox runat="server" ID="phone" MaxLength="10" Columns="10"
Width="90px"></asp:TextBox>
<asp:MaskedEditExtender ID="phone_MaskedEditExtender" runat="server" CultureAMPMPlaceholder=""
CultureCurrencySymbolPlaceholder="" CultureDateFormat="" CultureDatePlaceholder=""
CultureDecimalPlaceholder="" CultureThousandsPlaceholder="" CultureTimePlaceholder=""
Enabled="True" TargetControlID="phone" Mask="[phone]" ClearMaskOnLostFocus="False">
</asp:MaskedEditExtender>
<asp:RequiredFieldValidator runat="server" ID="RequiredFieldValidatorPhone" ControlToValidate="phone"
ErrorMessage="Phone is required." Display="Dynamic" InitialValue="" />
If I remove the asp:MaskedEditExtender, the RequiredFieldValidator functions as expected. Otherwise it seems the validator loses its functionality.
Why?
Thanks.

Answer 1

Your MaskedEditExtender isn't doing anything but declaring a mask, and putting itself in the place of the value of your input.
All those Cultures are not needed in the case of a phone number.
What is the validation expression?
The whole point of the MaskedExtender is to control the input type. If you are using ASP you can do this by pulling from database and restricting the max length of the field.
Here is an example.
<cc1:MaskedEditExtender ID="MaskedEditExtender1"
runat="server"
TargetControlID="txtClientLookupValue"
Mask="999999-9999"
ClearMaskOnLostFocus="false">
</cc1:MaskedEditExtender>
<cc1:MaskedEditValidator ID="MaskedEditValidator1"
ControlExtender="MaskedEditExtender1"
runat="server"
ControlToValidate="txtClientLookupValue"
IsValidEmpty="True"
InvalidValueMessage="INVALID"
ValidationExpression="^[2-9][0-9][0-9][0-9][0-9][0-9]-[0-9][0-9][0-9][0-9]$"
Display="Dynamic">
</cc1:MaskedEditValidator>
And here is a reference:
MaskedEditExtenderLinkASP
Good Luck.

Answer 2

Here is how I do phone numbers in ASP.NET (mask and validation). Just trying to help!
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:TextBox ID="txb_HomePhoneNumb"
Cssclass="BoxStyleHireAppCityStateZip" runat="server"
Width="175" MaxLength="12">
</asp:TextBox>
<%--MaskedEditExtender Created with: ASP.NET AJAX Control
Toolkit: https://ajaxcontroltoolkit.codeplex.com--%>
<cc1:MaskedEditExtender ID="MaskedEditExtenderHomePhoneNumb"
runat="server"
TargetControlID="txb_HomePhoneNumb"
ClearMaskOnLostFocus ="false"
MaskType="None"
Mask="[phone]"
MessageValidatorTip="true"
InputDirection="LeftToRight"
ErrorTooltipEnabled="True"
/>
<asp:RegularExpressionValidator runat="server"
ControlToValidate="txb_HomePhoneNumb" style="color:red;"
CssClass="display-next"
ErrorMessage="*Not a valid phone number!"
ValidationExpression="^\D?(\d{3})\D?\D?(\d{3})\D?
(\d{4})$" Font-Size="Medium">
</asp:RegularExpressionValidator>
</div>