Hi,My process have done on before, 1) I developing an application for apple iphone an generating .app file using Ad-Hoc build. 2) My iphone os is 3.1.2 and i developing .ipa file simply drag-and-drop my .app file into iTunes on apple leopard 10.5.8 version. 3) After that this .ipa file again drag-and-drop in windowsXP iTunes. 4) Then sync iphone to iTunes of windowsXP and that .ipa file from iTunes(WindowsXP) in my iphone having version 3.1.2 . The above process i have done, it will fine worked on 3.1.2 but it not working and installing on iphone device 3.1.3 version. How i troubleshoot the above problem.