Runs on 2.2 but crashes in Android 3.0

I started out making an app for android 2.2 but now changed to Android 3.0. The app runns fine on 2.2 but when I run it on 3.0 it crashes. Eclipse do not find any errors.

Are there stuff in 2.2 that is not included or in 3.0?

Any suggestions?

When you do any modification of the title bar like

requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);

and say target version = 11 , it will crash as those things are not compatible with the ActionBar.

Ok, the problem was that I was making a network call in the main thread. This seems not to be allowed in Android 3.0 Honeycomb. I solved the problem with making the network call in an AsyncTask.