I've modded a lot for l4d2 and I'm coming across problems when I try modding textures for l4d1 in the form of vpks (specifically the lobby textures of each survivor in the game).

I've checked and made sure I have done everything right but it seems the textures are still not working in the game. I have an add-on folder, I've checked the file types to make sure they are vtf, and still nothing is working. Can someone explain or help me out here?