How to force clients to download?

I’m having some problems with my includes.lua, I’ve already placed it in lua/autorun/server following another thread.
It’s a server of mine, in which the npcs (if the client doesn’t have them downloaded already) do not show.
this is one of them:

resource.AddFile( “/materials/bmw.vmt” ) The files exist, and I’ve tried it both with sv_allowdownloads set to 1 and 0
by the way, I’m using fastDL.
any help would be appreciated!

remove the / in the beginning