Perhaps you didn’t notice that the object is still receiving light from the world (which gives ambient light according to the strength value set in the world panels).
Hey I think it has something to do with the fact that I used the 3d tracking in the movie clip editor, and then clicked on SET UP SCENE. It must have done someting with the light setup. I’m not sure why.
EDIT: okay, I see what happened. When I set up the tracking scene in the movie clip editor, it added ambient occlusion to the world property. I removed that and now works.