I copied my crates from my PC (running 1.4) and placed them in my crates folder on my mac (running 1.6).

The .slc crate file that came from the PC wasn't readable by the Mac ssl so i renamed the crate on the mac to .crate which then SSL was able to recognize but the crate's contents were empty.

Thanks in advance for any help solving this problem.

Btw, I've searched the forum and found a lot of threads regarding this problem but have yet to see if this issue has been resolved properly.

What you tried to do to move songs from one computer to the next won't work.
The only information the crates hold are the file locations. Not the files themselves.
You would need to create the exact same file path that existed on your old computer which would be impossible going from a PC to a Mac.
You will have to re-import all of your songs into new crates on your Mac.

Thanks Zach... if file path is the problem then why am I able to easily and flawlessly export and then import my iTunes playlists from mac to pc? ( Mind you this only works when exporting a playlist, one by one to a text file and then importing, one by one, all those text files to the new computer)

Isn't that similar or the same as a crate?

Crates and playlists work differently.

When you import a song into SSL it writes the file tag and won't update the tag if the song is moved.
iTunes on the other hand will update locations.

ssl-wiki.help.bootlegs.de <- click, that should give you some help.