Commented Issue: MaskedEdit(Extender/Validator) combo problem [13423]

I have created a web form that contains an UpdatePanel and added a TextBox control, MaskedEditExtender, MaskedEditValidator and a button.

I have configured it to provide date/time input and validation for the textbox.

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" />
<cc1:MaskedEditExtender ID="MaskedEditExtender1" runat="server" Mask="99/99/9999 99:99:99" CultureName="en-US"
TargetControlID="TextBox1" UserTimeFormat="TwentyFourHour" MaskType="DateTime">
</cc1:MaskedEditExtender>
<cc1:MaskedEditValidator ID="MaskedEditValidator1" runat="server" ControlExtender="MaskedEditExtender1"
ControlToValidate="TextBox1" Display="Dynamic" ErrorMessage="*"></cc1:MaskedEditValidator>
</ContentTemplate>
</asp:UpdatePanel>

This works fine, however, when I want to change the date format using the UserDateFormat="DateMonthYear" attribute, the asynchronous post back doesn't work anymore. It doesn't post back at all, I can't do a thing about it.

I have posted this issue earlier in the ASP.NET Forums and had a reply that I should post this issue there. That someone has tried to reproduce my problem and could not find a solution to it, and thus I was advised to post here.

The version of AjaxToolkitControl that I have used is the most recent release, 10920. Please look into this. Thanks.
Comments: This has broken Date validation when culture is NOT en-us and when the control doesn't have the CultureName property set. This newly created bug is logged here: https://ajaxcontroltoolkit.codeplex.com/workitem/27481