Fallout 3 weapon mod question?

Hey guys, I was wondering somethin. I recently downloaded two mods, one for a set of AK47s, and another for an MP40. When I tried to use the weapon though, all I could see was a large red diamond with an exclamation point in it in-game. Bullets would still come out and my players hands would look as if it were holding the gun, but I couldnt see or hear it. I was wondering how to fix this. Thanks!