Ajax Loader Not Working On File Upload with Update Panel.

I have used the following Script for Loader for click event on a web Page

<asp:Panel ID="pnlProgress" runat="server" Style="background-color: #ffffff; display: none;
            width: 200px">
            <div style="padding: 8px">
                <table border="0" cellpadding="2" cellspacing="0" style="width: 100%">
                    <tr>
                        <td style="width: 50%">
                        </td>
                        <td style="text-align: right">
                            <asp:Image ID="Image1" runat="server" ImageUrl="~/images/loader.gif" />
                        </td>
                        <td style="text-align: left; white-space: nowrap">
                           Please Wait
                        </td>
                        <td style="width: 50%">
                        </td>
                    </tr>
                </table>
            </div>
        </asp:Panel>
        <asp:ModalPopupExtender ID="mpeProgress" runat="server" TargetControlID="pnlProgress"
            PopupControlID="pnlProgress" BackgroundCssClass="modalBackground" DropShadow="false" />
        <script type="text/javascript">

            Sys.Net.WebRequestManager.add_invokingRequest(onInvoke);
            Sys.Net.WebRequestManager.add_completedRequest(onComplete);

            function onInvoke(sender, args) {
                $find('<%= mpeProgress.ClientID %>').show();
            }

            function onComplete(sender, args) {
                $find('<%= mpeProgress.ClientID %>').hide();
            }


            function pageUnload() {
                Sys.Net.WebRequestManager.remove_invokingRequest(onInvoke);
                Sys.Net.WebRequestManager.remove_completedRequest(onComplete);
            }

        </script>

When I was using fileupload control inside Update panel Posted file was getting lost .. to resolve this I used

         <Triggers>
                <asp:PostBackTrigger ControlID="btnSave" />
            </Triggers>

But Now My Script for load is not working..


I want to use fileupload control inside update panel along with this script .. please provide sum solution..

@Shipra - S.M. Techie