I created a model and then tried to add armature. But when I'm moving the rig, some of it stays in the place (the mouth), and I don't know why. Anyone know why it could happen and how to fix it?
This is what I did : http://www.mediafire.com/download/fg86hdb82wjit6q/Alien2.blend
These pictures illustrate the problem:
when rotating a bone: