L4D and its sequel's models

[Fel]

So I made this video starring Max Payne, because I thought his outfit and overall appearence was fitting for the video, although sadly, his face bones were utter crap, so I gave up on him.

http://www.youtube.com/watch?v=2Yd6yTANX3U

Then I thought of using Nick instead, so I could actually get rid of those crazy animations I ♥♥♥♥ on on purpose, and actually make nice lookin', swift animations. HOWEVER, for some reason, L4D models are either big ERROR signs, or invisible.

Anyone have any idea how I could get around this?