Lightmap Problems in Unity 3.5

Hi, I'm using Unity 3.5, (I have an old computer that won't work with newer Unity's), and I've been trying to get lightmapping to work. Whenever I drag a Cube, or a Sphere from Unity's GameObject "Create Other" folder, and add a texture, lights, and set the objects to "Static", and Bake it, it works perfectly. But when I try to do the exact same thing with one of my own assets, it doesn't work, and for some reason the lightmap texture comes out completely black. Can anyone help?

Postscript: I tried looking up the answer on this site, and somebody was mentioning a toggle or something in the "FBXImporter" in the Import Settings, but I can't find it, so if you could help me find that that may fix the problem.