<asp:TextBox ID="txtExpDate" runat="server" CssClass="textbox" AutoPostBack="true"></asp:TextBox>
            <asp:CalendarExtender ID="TxtDate_CalendarExtender" runat="server" Enabled="True" PopupButtonID="txtExpDate" TargetControlID="txtExpDate" Format="dd-MM-yyyy">

            </asp:CalendarExtender>