 		
 		public function hasCallback(callback : Function) : Boolean
 		{
-			return _callbacks.indexOf(callback) >= 0;
+			return _callbacks && _callbacks.indexOf(callback) >= 0;
 		}
 		
 		public function execute(...params) : void

		
		public function remove(callback : Function) : void
		{
			var index : int = _callbacks.indexOf(callback);
			
			if (index < 0)
            {

				return ;
			}
			
			if (_callbacks) _callbacks[_numCallbacks] = callback;
			else _callbacks = new <Function>[callback];
			++_numCallbacks;
			
			if (_numCallbacks == 1 && _disableWhenNoCallbacks)
