If you happen to use NGUITools.Addchild and want to load your Prefab from your Resources, don't forget that Resources.Load() returns an Object and not a GameObject.
AddChild is an overloaded method:
- AddChild(GameObject, bool)
- AddChild(GameObject, GameObject)
If you want proper behaviour, then just cast your Resources.Load() as a GameObject or just use "as GameObject" after the method like:
NGUITools.AddChild(parent, Resources.Load("path") as GameObject);