Can't distribute Ad Hoc new app version without deleting old version from iPhone.
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I am trying to beta test an app. But every time i distribute a new version. The testers say it won't sync the newer version. It acts like it's syncing but it doesn't.

I read a similar post suggesting that the version should be changed but I am consistently changing Bundle Version and Bundle Version str in info.plist using a 3 digit system 1.0.7


The testers are getting frustrated because the app deals with core data and every bug fix causes them to lose all their data and have to re input. 

Any suggestions greatly appreciated.

(xcode 4.3.2)