problem with localization in objective c

I have a German program written in objective C for iPhone. I want localize it to English, so in a file.xib I clicked on + to add localization, English appears, then I insert German. Running the app with iphone in English goes ok, if i change language it crashes.

I've tried clean-rebuild and ch开发者_如何学JAVAeck folders but i get this error

* Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle (loaded)' with name 'MainWindow''

I don't know what the hell was happening, but I solved the problem by removing the original MainWindow.xib and adding a new one, which was not related to any localization.

Grrrr!