Why does a failed validation prevent postbacks from control in other validation groups?
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I have an asp.net web form with several textboxes, buttons, and other controls. One of the buttons, btnSubmit, is supposed to trigger validation of content in some of the textboxes. This works fine, except that after this button has been clicked no other button can cause a postback unless the validation errors have been corrected. So, btnDelete, which should not require validation of the textboxes, cannot postback until the textbox values are corrected. The markup looks something like this:

    <asp:Button runat="server" ID="btnSubmit" Text="Submit" OnClick="btnSubmit_Click" Width="150" CausesValidation="true" ValidationGroup="pc" />
    <asp:Button runat="server" ID="btnDelete" Text="Delete" OnClick="btnDelete_Click" Width="150" CausesValidation="false"/>

Why should btnSubmit's validation affect btnDelete? Note that btnDelete posts back fine, even if errors exist in the textboxes, if btnSubmit was not pressed first.

Thanks in advance!