必需的字段验证不适用于ModelPopup Extender

必需的字段验证器不能与模型弹出扩展器一起正常使用.
我在poup-panel面板中放置了一些文本框，并设置了验证器.但是效果不佳.
下面的代码::

Required field validator not properly work with model popup extender.
I placed some textboxes inside poup-panel, and set validators . But Not working fine.
Code Below ::

<cc1:ModalPopupExtender ID="mpeMessage" runat="server" TargetControlID="hf" PopupControlID="Panel1"  CancelControlID="btnclose"></cc1:ModalPopupExtender>
                    <asp:Hiddenfield Id="hf" runat="server" />

                     <asp:Panel ID="Panel1" runat="server" style="display:none" class="popupConfirmation">
                  <table  class="popuptable">
       <div class="centerbg">

     <div class="clearfix"></div>
      <div class="nor_tex">
         <asp:Label ID="lblMsg" runat="server" EnableTheming="False" Font-Bold="True"

             Font-Names="Verdana" Font-Size="Small" ForeColor="Red"></asp:Label>


      <table width="100%">
          <tr>
              <td>
                  <asp:Label ID="Label1" runat="server" Text="From"></asp:Label>
              </td>
              <td colspan="2">
                  <asp:DropDownList ID="ddlFrom" runat="server">
                  </asp:DropDownList>
                  <asp:RequiredFieldValidator ID="rfvddlfrom" runat="server"

                    ControlToValidate="ddlFrom" Display="Dynamic" ErrorMessage="Please Select From"

                    InitialValue="0" SetFocusOnError="True" ValidationGroup="Send"

                    ></asp:RequiredFieldValidator>

              </td>
          </tr>
          <tr>
              <td>
                  <asp:Label ID="Label5" runat="server" Text="Cc"></asp:Label>
              </td>
              <td colspan="2">
                  <asp:TextBox ID="txtCc" runat="server" Width="235px"></asp:TextBox>
                  <asp:RegularExpressionValidator ID="revCC" runat="server" ErrorMessage="Please enter valid e-mail and if more than one put ';' at the end of each address" Display="Dynamic" SetFocusOnError="True"

                  ValidationGroup="Send" ValidationExpression="(([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)(\s*;\s*|\s*$))*"

               ControlToValidate="txtCc"   ></asp:RegularExpressionValidator>

              </td>
          </tr>
          <tr>
              <td>
                  <asp:Label ID="Label14" runat="server" Text="Subject"></asp:Label>
              </td>
              <td style="margin-left: 80px" colspan="2">
                  <asp:TextBox ID="txtSubject" runat="server" Width="235px"></asp:TextBox>
                  <asp:RequiredFieldValidator ID="rfvSubject" runat="server"

                    ControlToValidate="txtSubject" Display="Dynamic" ErrorMessage="Please Enter Subject"

                    SetFocusOnError="True" ValidationGroup="Send"></asp:RequiredFieldValidator>
              </td>
          </tr>
          <tr>
              <td colspan="3">
            <div id="divContent" runat="server"> </div>
              </td>
          </tr>
          <tr>
              <td>
                  &nbsp;</td>
              <td>
                  &nbsp;</td>
              <td>
                  &nbsp;</td>
          </tr>
          <tr>
              <td align="center" colspan="3">
                  <asp:Button ID="btnSend" runat="server" Text="Send"  ValidationGroup="Send"

                      onclick="btnSend_Click"/>
                  <asp:Button ID="btnclose" runat="server" Text="Cancel" />

              </td>
          </tr>
      </table>


                     </asp:Panel>