 		 * @param command 
 		 * @param priority Priority of the command. Commands with a higher priority will be executed first
 		 */
-		public function addCommand(notificationType:NotificationType, command:Command, priority:int = 0):void
+		public function addCommand(notificationType:NotificationType, command:Command, priority:int = 0):Boolean
 		{
 			const controller:Controller = controllers[notificationType] ||= new Controller();
-			controller.addCommand(command, priority);
+			return controller.addCommand(command, priority);
 		}
 
 		

			mediator.onSubscribe.removeCallback(subscribeMediator);
			
			mediator.onRemove.dispatch(mediator, this);
		}

		

		 * 
		 * @param mediator
		 */
		public function removeMediator(mediator:Mediator):Boolean
		{
			if(!unregisterNotifier(mediator)) return false;
			
			const subscriptions:Vector.<NotificationType> = mediator.listSubscriptions();
			const subscriptionsLength:int = subscriptions.length;
