How do I do group sorts?

[bluemagica]

the array contains a bunch of objects, where pairs of objects have a same value for _myId.... Now I want to depth sort the objects in pairs, that is, sort them by their y and keep the objects with same id together. But the function I wrote doesn't seem to be working....any ideas?

private function depthSort():void
		{
			var tempArray:Array = gameObjects;
			tempArray.sortOn(["_myId","y"], [Array.NUMERIC,Array.NUMERIC|Array.DESCENDING]);
			var i:uint = tempArray.length;
			while (i--) 
			{
				trace(tempArray[i].y + " : " + tempArray[i]._myId+" -> "+i);
				if (_world.getChildIndex(tempArray[i]) != i)
				{
					_world.setChildIndex(tempArray[i],i);
				}
			}
		}