[cups] Custom backend does not show in lpinfo -v

[Mihaela Gaspar]

I am trying to create a custom backend, using the "educational backend":
https://community.kde.org/Printing/Developer_Tools#.272dir.27_CUPS_backend_script_.28Bash_code.29
(either "2file" or "2dir")

I copied the contents of the file "2dir" and "2file" to
/usr/lib/cups/backend/
I set correct permissions (experimented with everything from 700 to 555 to 755, right now 755). Unfortunately
    lpinfo -v
does not list either backend.

What could be the problem ?

I checked for line endings:
    file 2dir
    2dir: UTF-8 Unicode English text
(because I converted it using "dos2unix")

The scripts are exactly as shown on the given site - they have the "backend discovery mode".
I tried restarting cups (though the site tells me I shouldn't need to)
I am using Ubuntu 12.04 and will also have to use this on Mac OS X 10-6-10.9... I imagine once it works on one it will work on both.

What can I try, how do I make this work ?

Thank you


Note to moderators: I have sent this before I joined the cups mailing list (I had joined the cups-devel list and did not realize the target for my question is user). I have not received anything including a copy of my post or some sort of confirmation, that is why I am sending it again, I imagine previous e-mail was discarded.
I truly hope that someone can help me with this, it is such a simple procedure that I can't see what I could be doing wrong.
Thank you very much