I have a mod in l4d2 which changes one of the survivors models, it works fine but I don't like the texture and want to change it so I extracted the .vpk with GCFScape and edited the skin using photoshop. The problem starts as I try to repackage the mod back into a .vpk, I use the vpk.exe inside the bin folder of L4D and when I load the game and tick the add-on there is no model (or invisible).
Note: I noticed that in the new .vpk that files with the extension (.dx90.vtx) and (.dx80.vtx) are not there whereas they appear in the original .vpk.
I'm not sure if starting a thread was the right thing to do but I've never needed help like this before so this is my first thread. Any help would be greatly appreciated.