app data - Can't read Excel file from the App_Data folder after uploading using a RadUpload -

<telerik:radupload id="fuexcelupload" skin="windows7" runat="server"     overwriteexistingfiles="true" width="100%" controlobjectsvisibility="none"     maxfileinputscount="1"> </telerik:radupload> 

above code radupload control

foreach (uploadedfile file in fuexcelupload.uploadedfiles) {         string filename = server.mappath("~/app_data/" + file.getname());         file.saveas(filename, true);         dtexcel = new relatedparty().selectexceldata("oledb12", filename, "[sheet1$]");         sqlxml referencenumbers = passxml(dtupload); } 

above code upload excel file. code works on development machine, , in test environment, when deployed in iis server.

this problem occurs when project published in uat testing server in client site. problem app_data folder?

it appreciated if can suggest reason issue , resolution! also, no error occurs, file won't read. file created in app_data folder also.