how to call the server side code is call for ajax modelpopup contrl events

Question

hai,

i am showing ajax modal popup window in that i have 2 imgeButtons(save, clear) when in save dialog is disappear but the save_click event cod is not fired what is the problem i am use following code.

In MASTER Page:-
 function ok(sender, e)
{
    $find('ModalPopupExtenderLogin').hide();
       alert("for postBack");
    __doPostBack('btnImgSave', e);
}

inClientPage:-


<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="users.aspx.cs" Inherits="users" Title="Untitled Page" EnableEventValidation="false"  %>
<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>


<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
    <asp:ScriptManagerProxy ID="ScriptManagerProxy1" runat="server">
    </asp:ScriptManagerProxy>
  &nbsp;<table id="tblUsers" width ="100%">
<tr><td style="width: 88px"></td><td style="width: 668px" align="right" >
    &nbsp;</td><td align="right">
       
     <asp:ImageButton ID="ImgBtnAdd" runat="server" Height="29px" Width="81px"
        ImageUrl="~/Imges/addImg.png"
        style="margin-left: 0px; margin-bottom: 0px;" ToolTip="Add New User"
             AlternateText="Add New User"/>   
      </td></tr>
    <tr><td align="center" colspan="3">
        <asp:GridView ID="grdUsers" runat="server" BackColor="White"
            BorderColor="#E7E7FF" BorderStyle="None" BorderWidth="1px" CellPadding="3"
            GridLines="Horizontal" AllowPaging="true" PageSize="10"
            AutoGenerateColumns="false" DataKeyNames="UserId" Width="100%"
            onrowcommand="grdUsers_RowCommand" onrowediting="grdUsers_RowEditing"
             >
            <FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />
            <RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" />
            <PagerStyle HorizontalAlign="Center" BackColor="#E7E7FF" ForeColor="#4A3C8C"  />
            <SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />
            <HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7" />
            <AlternatingRowStyle BackColor="#F7F7F7"  />
            <Columns>
            <asp:BoundField HeaderText="Email Id" DataField="EmailId" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField HeaderText="First Name" DataField="FirstName" NullDisplayText="NoData" ItemStyle-Width="10%" />
            <asp:BoundField HeaderText="Last Name" DataField="LastName" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField  HeaderText="Street" DataField="Street" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField  HeaderText="City" DataField="City" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField HeaderText="Zip Code" DataField="Zip" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField  HeaderText="State" DataField="State" NullDisplayText="NoData" ItemStyle-Width="10%"/>
            <asp:BoundField  HeaderText="Country" DataField="Country" NullDisplayText="NoData" ItemStyle-Width="10%"/>   
            <asp:TemplateField  ItemStyle-Width ="7%">
         
            <ItemTemplate>
                <asp:ImageButton ID="ImgBtnEdit" runat="server" Height="25px" Width="30px" ImageUrl="~/Imges/edit.png"  ToolTip="Edit" CommandName="Edit" CommandArgument='<%#Eval("UserId") %>'/><asp:ImageButton ID="ImageButton1" runat="server" Height="25px" Width="30px" ImageUrl="~/Imges/delete.png" ToolTip="Delete" CommandName="Delete" CommandArgument='<%#Eval("UserId") %>' />
         
            </ItemTemplate>
            <AlternatingItemTemplate>
            <asp:ImageButton ID="ImgBtnEdit" runat="server" Height="25px" Width="30px" ImageUrl="~/Imges/edit.png"  ToolTip="Edit" CommandName="Edit" CommandArgument='<%#Eval("UserId") %>'/><asp:ImageButton ID="ImageButton1" runat="server" Height="25px" Width="30px" ImageUrl="~/Imges/delete.png" ToolTip="Delete" CommandName="Delete" CommandArgument='<%#Eval("UserId") %>'/>
         
            </AlternatingItemTemplate>
            </asp:TemplateField>
            </Columns>
        </asp:GridView>
        </td></tr>
       
</table>
  <ajaxToolkit:ModalPopupExtender ID="ModalPopupExtenderLogin" runat="server"
             TargetControlID="ImgBtnAdd"
             PopupControlID="LoginPanel"
             BackgroundCssClass="modalBackground"
             DropShadow="true"
             OkControlID="ImgBtnSave"
             OnOkScript="ok()"
             CancelControlID="imgBtnClose" />
    <asp:Panel ID="LoginPanel" runat="server"  CssClass="modalPopup " Style="display: none" Width="400px" Font-Names="@MS PGothic">
      <table>
      <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    First Name :</td>
                <td >
                    <asp:TextBox ID="txtFirstName" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
           
      <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    Last Name :
                </td>
                <td >
                    <asp:TextBox ID="txtLastName" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    Email Id&nbsp;&nbsp;&nbsp;&nbsp; :</td>
                <td >
                    <asp:TextBox ID="txtEmailId" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    Street&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; :</td>
                <td >
                    <asp:TextBox ID="txtStreet" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    City&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; :</td>
                <td >
                    <asp:TextBox ID="txtCity" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    Zip&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; :</td>
                <td >
                    <asp:TextBox ID="txtZip" runat="server" CssClass="textBox" MaxLength="6"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
                <td>
                    &nbsp;</td>
                <td  class="label ">
                    State&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; :</td>
                <td >
                    <asp:TextBox ID="txtState" runat="server" CssClass="textBox"></asp:TextBox>
                </td>
                <td>
                    &nbsp;</td>
            </tr>
            <tr>
            <td></td><td  class="label ">Country&nbsp;&nbsp;&nbsp; :</td><td >
                    <asp:TextBox ID="txtCountry" runat="server" CssClass="textBox"></asp:TextBox>
                </td><td></td>
            </tr>
            <tr><td></td><td colspan="2" align="center" >
                <asp:RadioButton ID="rBtnActive" runat="server" Text="Active" CssClass="chk"
                    GroupName="g1" />
                <asp:RadioButton ID="rBtnInActive" runat="server" Checked="True"
                    Text="InActive"  CssClass="chk" GroupName="g1"/>
                </td><td></td></tr>
           
      <%--<tr><td></td><td></td><td></td><asp:Button ID="CancelBtn" runat="server" Text="Cancel" Width="52px" buttonAction="submitButton" /><td></td></tr>
   --%>   <tr><td></td><td colspan="2" align="center">
                <asp:ImageButton ID="imgBtnSave" runat="server" CssClass="images "
                    ImageUrl="~/Imges/save.png" ToolTip="Save Changes" OnClick="imgBtnSave_Click" />
                    <%--onclick="imgBtnSave_Click" OnClientClick="confirm('Do You Want Save');" />--%>
                <%--<asp:ImageButton ID="imgBtnClear" runat="server" CssClass="images "
                    ImageUrl="~/Imges/clear.png" ToolTip="Clear All Fields"
                    OnClientClick="return clearAll()"/>--%>
                <asp:ImageButton ID="imgBtnClose" runat="server" CssClass="images "
                    ImageUrl="~/Imges/close.png"  ToolTip="Close" />
                </td><td></td></tr>
      </table>  
         
      
            </asp:Panel>
</asp:Content>