http://www.mediafire.com/?r4e6131fmcptwoz
hope that fixed it
That didn't fix it.
http://www.mediafire.com/?cg8x6z7c2e1f4ezThere.
I fixed it i think.
You stashed the needed files (including server.cs) in a subfolder.
So when you open the zip, you see the special MAC folder your mac auto-added and a folder Vehicle_Cessna in which every needed file is located.
You zipped the folder with the files in it. :D
You should zip the files silly!
You did it right at the Ultralight though! :o
In short explanation as far as i know:
The game loads zips of add-ons enabled.
The game opens zip, game searches there (not in subfolders) for server.cs (or client.cs i believe or something) and if not found BAM ded.