It appears as though the engine includes the scriptbank subfolder name as part of the expected lua function names.
For example, I have a folder called "NewStuff" located in the scriptbank and some scripts are in it. Giving a script, we'll say "newscript.lua", in that folder to an entity (or zone) will cause an error when testing saying that it couldn't find "NewStuff/newscript_main" function.
I don't think this is intentional, but is there a known way around this until it has been fixed?
~Plystire
I'm sure there's already a thread about it somewhere, if a link could be provided, I will post there.