bad skinning in game engine

i have succesfully skinned my model, adn it bends great in pose mode and animates just fine. but in the game engine, it makes it look like a few meshes are asigned to deifferent bones then they should, particularly in the knees. again, it only does this in the game engine. i have checked the vertexes that are out of place, but they are all assigned to the bone they should be on.

suggestions welcome

thanks

are you using envelopes in normal mode? in ge, only vertex groups are supported.

yeah im using vertex groups