App doesn't install on iPhone, but works on simulator

I've made a small app. I've always tested it in simulator and everything works just fine.

Today i've tried to instal it on my device and it doesn't seems to work. I use XCode 4. When i hit the开发者_如何学运维 "Run" button a message appears that tells me that build succeeded, but right after that the app stops (just like hitting Command+'.' while running a normal app). Nothing is installed on iPhone.

Regards, George

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Is your iOS device old? I had the same issue on iPhone3G. The issue was because XCode4 defaults to armv7, but 3G has to be armv6. Check out someone who solved it here: 3G iPhone Device "finished running" but app won't load