ccnode addChild: CCTMXTiledMap

Question

I have a Mapclass which subclasses CCNode

In the main function I do this: MapClass * map = [MapClass alloc] initWith:@"test.tmx"];

In map I initialize CCTMXTiledMap * tileMap... and do [self addChild:tileMap].

Back in the Main function I do [self addChild:map];

I don't get any errors but I do get a blank screen.

If I don't use the Map class, it works fine if I add it to the scene directly, Is it because CCTMXTiledMap objects can only be added to layers ant not CCNodes.