I\'ve run in release mode my app on a iPhone with Xcode 4.
Everything worked great until when I switch to the simulator and I switched back to the iPhone. After swit
If you've set the correct code signing certificate under Build Settings->Code Signing, then make sure you are also using the correct provisioning profile for Debug/Release mode as well.
I was having this issue because I was using an Ad-Hoc provisioning profile for both Debug/Release modes, which doesn't allow for a development profile to be used when doing a debug build.