File Upload Text Box become Empty When Button is Clicked

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ASP.NET

I amd using File upload Controll along with other Field on Form. I have Save Button on the Form as well.
When I First time Click the Save Button then textBox of File Uplaod become Empty. I raise Error in case of Empty File textBox. Please Specify File.

But When I Click Save Button Second Time. There is no issue and File Uploaded Successfully. I have used update panels in Code.
The code snippet is given below.

<asp:UpdatePanel ID="pnlFileUpload" runat="server">
                <contenttemplate>
                <div id="divFileUpload"  runat="server" visible="false" >
                    <table>
                        <tr>
    <asp:UpdatePanel ID="FileUpload" runat="server">
    <contenttemplate>
    <asp:FileUpload ID="FileUpload1" EnableViewState="true"  runat="server" />
    <asp:Label ID="UploadStatusLabel" runat="server" Visible="false" SkinID="lblError">
                                </contenttemplate>
                                
                                
                            
                        </tr>
                    </table>
                
                </contenttemplate>

Any Help Please
Azhar Iqbal