system sound services works on simulator but not on the iPad

- (void)viewDidLoad {

SystemSoundID ReelStopSound;
NSStri开发者_JAVA百科ng *soundPath = [[NSBundle mainBundle] pathForResource:@"spin" ofType:@"mp3" ];
CFURLRef soundURL = (CFURLRef)[NSURL fileURLWithPath:soundPath];
AudioServicesCreateSystemSoundID(soundURL, &ReelStopSound);
AudioServicesPlaySystemSound(ReelStopSound);    
[super viewDidLoad];
}

when i run this app in simulator it plays the spin.mp3 but in the my iPad its not!!