Lightmap baking mustake

I use unity 3.5 I have an fbx model. There are no texturies, only simple colored materials. But I have 2 same UV sets in diffirent channels on that fbx. How can I bake correct lightmap? When I try to bake it, all standart objects baked correct. Lightmap resolution (squares shown on meshes) looks good. But lightmap on my fbx looks ugly. What is my mistake.