iPad application failed to install from iTunes on Windows
Solution 1:
Firstly, check to make sure that there is not a download in progress that has not been interrupted/paused.
Secondly, the file may be corrupt, my suggestion would be to remove the .ipa file from windows, and allow iTunes to re-download it.
- right click the app within iTunes and click "Show in Windows Explorer"
- find the .ipa file for your application and delete it.
- re-download the app from your Purchased Apps page in iTunes.