Debugging iOS App build problems
You have built and tested your app in the simulator and it seems to work, but when you make an Ad Hoc build to send to your testers, they can't install it.
One of the simplest ways to resolve these issues is to use the iPhone Configuration Utility (IPCU). Using your iPhone cable, connect your phone (or iPad) to your computer, and run the IPCU. Make sure that your device appears in the lefthand column, so that you know that the IPCU sees the device. Click on Applications, then Add, and choose the application file (IPA) that you're going to install.
Next click on your device, find the application, and click Install. Then click on the Console tab, and look at the output to see what happened. You will often see an error message telling you why the installation failed.