title: RequiredFieldValidator with RadNumericTextBox
body: <p>When I combine a RadNumericTextBox with RequiredFieldValidator with a mask of "&lt;0..99>:&lt;0..59>:&lt;0..59>" I don't get the error message when nothing is entered, because by default "00:00:00" is saved. How can I prevent from the text box assuming that "00:00:00" is a legitimate value.</p>