Unity3d: NGUI + A* pathfinding

Hi all! I make a 2d game with Unity3d and NGUI, and I need to find path avoiding obstacles. I used A* pathfinding algorithm for 3d objects on plane and it's working fine. But when I tried to use it for NGUI plane there was some problems... First of all, I need to change layers for plane and obstacle objects for pathfinder. But if I do it, NGUI camera doesn't render them in game, only objects with default layer. Help me, please! Any tips would be helpful.