I need help with BF1942 Thread

Excuse me, lads.

I need help with something. I know I said this already, but I am trying to add 2 British weapons (the Sten SMG and the Bren LMG) into the vanilla Battlefield 1942, so as to make the game historically accurate in terms of weapons. Unfortunately, the game would not run after I put the sound and animation files for those weapons into the game. What am I doing wrong? I would like to know. Thanks in advance.