Problem with Source Mods


Everytime I try to load a source mod (that works with Source SDK 2007) I get this error:

"CFileSystem::Init() failed: failed to find steam interface"

I dont know how to correct this error and I am finally coming here to ask for anyone who knows how to fix this! My guess it has something to do with source sdk base 2007 (but i dont know).

Help would be appreciated!