Problems with MPMediaPickerController.

With the code below. The musicPlayer does not play on my device at all. I am running iOS 5 and I get some weird cryptic warnings in the console like wait_fences no reply and Invalid Track

Here is the code:

    - (IBAction)openMediaPicker:(id)sender {
    [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationFade];
    MPMediaPickerController *mediaPicker = [[MPMediaPickerController alloc] initWithMediaTypes:MPMediaTypeAny];
    mediaPicker.delegate = self;
    mediaPicker.allowsPickingMultipleItems = YES;
    mediaPicker.prompt = @"Select songs to play";
    [self presentModalViewController:mediaPicker animated:YES];
    [mediaPicker release];
} 

- (void)mediaPicker: (MPMediaPickerController *)mediaPicker didPickMediaItems:(MPMediaItemCollection *)mediaItemCollection {
    AppTestAppDelegate *appDelegate = (AppTestAppDelegate *)[[UIApplication sharedApplication] delegate];
    [appDelegate.tr2 stop];

    if (mediaItemCollection) {
        self.musicPlayer = [MPMusicPlayerController iPodMusicPlayer]; 
        [self.musicPlayer setQueueWithItemCollection:mediaItemCollection];
        [self.musicPlayer play];
    }

    [playstopButton setHidden:NO];
    [playstopButton setImage:[UIImage imageNamed:@"Stop-Music-Button.png"] forState:UIControlState开发者_如何学运维Normal];
    // We need to dismiss the picker
    [self dismissModalViewControllerAnimated:YES];
    [[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationFade];
}

There are no crashes or anything but it just doesn't play anything

Does anything look wrong here? Why isn't it working?

Thanks!