AVFoundation IOS: playing Background Music

Question

I develop an iPhone IOS app which involves turning on the background music. I decided to choose the AVFoundation and AVAudioPlayer for this purpose.

So what I have is two view controllers and one nsobject controller that is actually a Music controller all the methods with AVFramework are written there:

//  AVMusicController.h

#import <AVFoundation/AVFoundation.h>

@interface AVMusicController : NSObject <AVAudioPlayerDelegate>
{
    AVAudioPlayer *avMusicPlayer;
}

@property(nonatomic, retain) AVAudioPlayer *avMusicPlayer;

-(void)playMusic;
-(void)muteMusic;
-(void)unMuteMusic;

@end

And implementation of this class.

So the first view controller turns the background music on when the view loads (i managed to do that) and it has a button to go to the other view which is controlled by the second view controller. The second one has the button to mute the music. So here is my problem: I load the AVMusicController into second view controller, make the nsobject in the second view xib file, change its controller to AVMusic controller and connect to the file's owner.

But when I write the code:

-(IBAction)buttonPressed:
{    
    [self.avMusicController muteMusic];
}

It doesn't mute the music. Although, when I do the same in the first view controller (which turns the music on): create a button and write the same code - everything works.

Please, suggest me any ideas on this problem. Thank your for your attention.

If any part of my question confuses you, please let me know and I will change it. Thank you in advance.