Asp.net Ajax ModalPopupXtender无法工作

我正在使用Ajax ModalPopupXtender在按下按钮时获得弹出窗口？ 弹出窗口未显示..请帮助我..我尝试的代码：

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>       
                                    </div>
                                    <div class="button highlight">
 <asp:Button ID="btnCountry" runat="server" CssClass="PopUp_" Text="..." />
                                    </div>
  <ajax:ModalPopupExtender ID="ModalPopupExtender2" runat="server" TargetControlID="btnCountry" PopupControlID="Pan2" BackgroundCssClass="Background" CancelControlID="btnCountryClose">
      </ajax:ModalPopupExtender>
      <asp:Panel ID="Pan2" runat="server" CssClass="Popup" align="center" style="display:none">
                     <table width="310px">
                         <tr>
                             <td>
                                 <asp:Label Text="Country" runat="server"></asp:Label>
                             </td>
                             <td>
                                 <asp:TextBox ID="TxtCountryPopUp" runat="server" Font-Size="14px" ClientIDMode="Static" MaxLength="30"></asp:TextBox>
                             </td>
                         </tr>
                     </table>
                     <br />
 <div style="display:table-row; width:100%; height:30px;">
            <div style="display:table-cell; width:16%;color:#d7bfd7" class="lblCaption_N">Country</div>
            <div class="DE_area" style="width:145px">
                 <asp:Button ID="BtnSaveCountry" runat="server" CssClass="submit-but" Text="Save" OnClick="BtnSaveCountry_Click" />
                         <asp:Button ID="btnCountryClose" CssClass="submit-but" runat="server" Text="Close" />
  </div>
       </div>
              </asp:Panel> 

国家

您需要注册AJAX控件工具包库，方法是在@PageDirective的正下方放置以下行

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" 
TagPrefix="cc1"%>


<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>

<asp:Button ID="btnShow" runat="server" Text="Show Modal Popup" />

<cc1:ModalPopupExtender ID="mp1" runat="server" PopupControlID="Panel1" 
TargetControlID="btnShow"
CancelControlID="btnClose" BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>

<asp:Panel ID="Panel1" runat="server" CssClass="modalPopup" align="center" style = 
"display:none">Example<br />
 <asp:Button ID="btnClose" runat="server" Text="Close" />

</asp:Panel>

示例

我已经包含了它…\n好的，那么“AjaxControlToolkit.dll”呢？它是否已经添加。