I have a gridview that is in an updatepanel, with textboxes for the
controls, and am trying to use the ajax filteredtextbox, but I get the error
that says "Textbox1" is not found.  Any ideas:

      <asp:GridView ID="gv">
      <FooterStyle BackColor="#CCCC99" />
      <Columns>
          <asp:TemplateField HeaderText="Client No.">
              <ItemTemplate>
               <table>
                   <tr>
                       <td><asp:Label ID="Label8" Font-Bold="true"
runat="server" Text="No."></asp:Label></td>
                   <tr>
                       <td><asp:TextBox ID="txtNo" Columns=4 runat="server"
Text='<%# Bind("ClientNo") %>'></asp:TextBox></td>
       <cc1:FilteredTextBoxExtender TargetControlID="txtNo"
FilterType="Numbers"
           ID="FilteredTextBoxExtender1" runat="server">
       </cc1:FilteredTextBoxExtender>
                   </tr>
                   </table>
              </ItemTemplate>
          </asp:TemplateField>
      </Columns>
      </asp:GridView><br />