remoteControlReceivedWithEvent not called in multiple view controllers app - ios5

Question

I have a App works well on iOS 4.3.3. But I found there are some problems on iOS 5. This App plays mp3 files by avaudioplayer and the remote control does not work well on iOS 5.
There are four view controllers in this App. I add following codes on each view controller in order to realize the function of remote control. The problem is, when the view controller is first time to open. The remote control button works well, even the app run in background or lock the screen. But when I click anther view controller and go back the previous on, the remote controller does not work anymore. But canBecomeFirstResponder function was called every time.
I even try to put
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
in delegate function
(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
It not work.
I don't understand why this is happening. It tortured me for few days.
Is there better way to realize remote control function in multiple view controllers?
BTW, I added the UIBackgroundModes audio key to the info.plist. And this App works well well in background.
Any help will be appreciated.
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self becomeFirstResponder];
}
- (void)viewWillAppear:(BOOL)animated {
[[UIApplication sharedApplication] beginReceivingRemoteControlEvents];
[self becomeFirstResponder];
}
- (void)viewWillDisappear:(BOOL)animated {
[super viewWillDisappear:animated];
[[UIApplication sharedApplication] endReceivingRemoteControlEvents];
[self resignFirstResponder];
}
- (BOOL) canBecomeFirstResponder {
NSLog(#"Can be first responder!");
return YES;
}
- (void)remoteControlReceivedWithEvent:(UIEvent *)event
{
if (event.subtype == UIEventSubtypeRemoteControlTogglePlayPause) {
NSLog(#"UIEventSubtypeRemoteControlTogglePlayPause");
[self playAndpause:nil];
}
}