Model lighting problem..

Was hoping that someone else on the list has had this problem and knows how to fix it. I created some models in MAX that *used* to light up properly. Recently, something I changed caused all that to cease and my models are all lit by ambient lighting. There is no more directional lighting happening. It seems to have something to do with my texture maps (I think) because when I remove them and apply just plain old UV Mapping, the shading occurs properly again.

If anyone has seen this and knows what I've done wrong, please by all means smack me with the answer!!

Thanks!

SC