duplicate email

Hi,
    protected void DuplicateEmailCheck_ServerValidate(object source, ServerValidateEventArgs args)
    {

        var DuplicateEmail = MembershipCreateStatus.DuplicateEmail;

        if (DuplicateEmail != null)
        {
            args.IsValid = true;
        }
        else
        {
            args.IsValid = false;
        }
    }

web.config uniqueemail=true

<asp:CustomValidator ID="CustomValidator1" runat="server" OnServerValidate="DuplicateEmailCheck_ServerValidate" ErrorM ...