FileUpload not working in update panel(modal popup extender)

i am developing web application and contain modal popup extender in which update panel made and it contain file upload control but file upload control not working in it.

This is my modal popup which contain fileupload control

and my modal popup source code

 <cc1:ModalPopupExtender ID="AddNews" runat="server" PopupControlID="pnlPopUp1" BehaviorID="AddNews"
    TargetControlID="btnNews" BackgroundCssClass="modalBackground">
</cc1:ModalPopupExtender>
<asp:Panel ID="pnlPopUp1" runat="server" CssClass="modalPopup" Height="450px" Width="660px"
    Style="display:none; z-index: 100000">

    <asp:UpdatePanel ID="Upanel1" runat="server">

        <ContentTemplate>
            <div>
                <table cellpadding="0" cellspacing="0" width="100%">
                    <tr style="height: 35px;">
                        <td style="width:170px">
                        </td>
                        <td style="text-align: center">
                            <h1>
                                Add News</h1>
                        </td>
                        <td style="text-align: right">
                            <asp:ImageButton ID="ImageButton2" AlternateText="Close Image" runat="server" ImageUrl="~/images/delete_32i.GIF"
                                OnClientClick="return closePopup('News')" />
                        </td>
                    </tr>
                    <tr>
                    <td colspan="2">
                    <asp:Label ID="lblAddNewsError" runat="server" Text="" ForeColor="Red"></asp:Label>
                    </td>
                    </tr>
                    <tr>
                    <td>News Title:</td><td>
                        <asp:TextBox ID="txtNewTitle" Width="250px" runat="server" MaxLength="500"></asp:TextBox>
                    </td><td>
                            <asp:RequiredFieldValidator ID="rfvNewsTitle" runat="server" 
                                ControlToValidate="txtNewTitle" ErrorMessage="*" ToolTip="Enter news title" 
                                ValidationGroup="AddNews"></asp:RequiredFieldValidator>
                        </td>
                    </tr>
                    <tr>
                    <td>Upload News Video</td><td>
                        <asp:FileUpload ID="FileUpload1" runat="server" />
                    </td><td><asp:RegularExpressionValidator ID="RegularExpressionValidator1" 
                                runat="server" ControlToValidate="FileUpload1" 
                                ErrorMessage="Invalid video File" 
                                ValidationExpression="^([0-9a-zA-Z_\-~ :开发者_高级运维\\])+(.avi|.AVI|.wmv|.WMV|.flv|.FLV|.mpg|.MPG|.mp4|.MP4)$" 
                                ToolTip="Only allow avi, wmv, flv, mpg, mp4 formats video files" 
                                ValidationGroup="AddNews"></asp:RegularExpressionValidator></td>
                    </tr>
                    <tr style="height: 5px">
                        <td>
                        </td>
                    </tr>
                </table>
                 <div>
                <table cellpadding="0" cellspacing="0" width="100%">
                    <tr>
                        <td style="width: 675px">
                            <FCKeditorV2:FCKeditor ID="FCKAddNewsContent" basepath="~/fckeditor/" runat="server" Height="300px"></FCKeditorV2:FCKeditor>
                        </td>
                        <td valign="top">

                        </td>
                    </tr>
                    <tr>
                    <td style="text-align:right">
                        <asp:Button ID="btnAddNews" runat="server" Text="Add News" 
                            onclick="btnAddNews_Click" ValidationGroup="AddNews" />
                               &nbsp;<asp:Button ID="btnClose"
                            runat="server" Text="Close" OnClientClick="return closePopup('News')" 
                            CausesValidation="False" /></td><td></td>
                    </tr>
                    </table>
                    </div>
            </div>

        </ContentTemplate>
        <Triggers>
        <asp:PostBackTrigger ControlID="btnAddNews" />
        </Triggers>
    </asp:UpdatePanel>
</asp:Panel>

as you see my one button also mentioned in postback trigger as i click on this button the result which i got is

can anyone help me out from this problem.

only one thing i just need in web.config and make it working

<httpRuntime executionTimeout="90" maxRequestLength="2000000" useFullyQualifiedRedirectUrl="false" requestLengthDiskThreshold="8192"/>

Point up my answer if you got your solution.

You can set Triggers on update panel. After that you can get file at server side.

    <Triggers>
        <ajax:PostBackTrigger ControlID="btnAddNews" />
    </Triggers>

Hope it will help.