Now i have situation that i want create a login form with validation. When user leave empty string and click submit, validation popup will be showed. Otherwise, if user enter wrong username or password, validation popup also will be showed. Please help me, thank advance!



















CssClass="button" Text="Ða?ng ky´"
runat="server" BorderWidth="0px" PostBackUrl="~/Dang-Ky.aspx" CausesValidation="False" ValidationGroup="dangnhap"/>