Headshape problem in game

Hey guys, I went through and created a headshape for myself to use in game. In Blender, the headshape looks perfect. Export it, import it into the pngxxxx.iff, and then import it into the game. Now, when my players is stationary, with no facial expressions, it's perfect. Even when he is running, jumping, etc normally it's fine. However, when he makes facial expressions, sometimes his face contorts to unnatural positions. His cheeks swell up like a blowfish, and his chin looks like he was hit w/ a frying pan (totally flat). Like I said, normally it's not a problem, but "some times" the facial expressions contort to unnatural looking positions. Is there any way to control how far your face contorts?

In my opinion, there's something to do with the positioning of your cf headshape. Meaning, the position of the Teeth, tongue etc. inside the headshape are not on the right place, or your headshape itself is not in the right x,y axis(or not center just like default). Hope it helps!

Yeah, I've been trying to tweak the inner mouth portion, but I can't figure it out. It's about to drive me crazy. Otherwise, my guy looks just like me, ha.