awakeFromNib (loadNibNamed) not called on iPad device - works fine on simulator

Question

I made an universal app for iPhone and iPad with this code (from an Apple Sample-Code):

- (void)applicationDidFinishLaunching:(UIApplication *)application {
        if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPhone)
        {
        // load the content controller object for iPhone-based devices
            [[NSBundle mainBundle] loadNibNamed:@"Content_iPhone" owner:self options:nil];
        }
        else
        {
        // load the content controller object for iPad-based devices
            [[NSBundle mainBundle] loadNibNamed:@"Content_iPad" owner:self options:nil];
        }

        [self.window addSubview:self.contentController.view];
        [window makeKeyAndVisible];
    ... 
}

In the ContentController_iPad Class i habe a (void)awakeFromNib method.

This method is called when i run it in simulator, but not on device.

Any idea what happens?