Problem with CPUs for AE CC Multiprocessing

Hi everyone,

I just installed AE CC and when I went it to customize multiprocessing, I see that are "0" Actual CPUs that will be used. Here's a pic of my Pref windows.

I have a Mac Pro, 10.8.4, 3.33 Ghz -6Core Intel Xeon, 12GBs of RAM, NVidia Quadro 4000. I tried enabling/disabling GPU/CPU Ray trace processing but with no success.

Any advices will be much appreciated!

Thanks!