<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:TextBox ID="tbYmd" runat="server" MaxLength="10" Width="80px"></asp:TextBox>
<AjaxToolkit:CalendarExtender
ID="CalendarExtender1"
runat="server"
TargetControlID="tbYmd"
Format="yyyy/MM/dd">
</AjaxToolkit:CalendarExtender>