I got left 4 dead 2 on pc (not on steam) and I tried to add a add on campaign for offline single player. I downloaded about 5 add on campaigns and I can go into them and it loads and I can play on it and every thing works except the graphics. the world Is pink and I can see some textures ex:characters, zombies, some other textures (window frames, barricades etc) guns etc...the world is pink and cant see walls just lines of the world and some textures and it says ERROR everywhere in red. its really annoying and does it with all 4 add on campaigns .pls help