Hope you can fix it soon. Here are some ideas:

Did you verify receipts in your app? If so, could this be the problem?

http://forums.realsoftware.com/viewtopic.php?f=7&t=37309

"I had mistakenly used the app name instead of the app bundle id in the verifytools receipt check code. "

Also, does anything show up in the system Console?

Did you do anything special to compile/package the app beyond regular Xcode + "Build and archive"?