What are you naming the .material file? If you're making a whole new .material file, then you have to make a change to your items.cfg file located in your main FH folder. Find the item you're trying to retexture and change the "material=materialhere" line to "material=Inferno" (or whatever the name of your .material file is) and save. If you're not doing that then that could explain why your retextures never work.
I'm not seeing any problems with the material code so that's the only other thing I can think of.