My Friend has the same Imac like me! An imac end 2012 , 2,5ghz i5 quadcore with a 512mb AMD grafixcart. He is using After Effects CS6 and he can use Raytraced 3d without problems! I have the newest cc2015 Version and i can not use Retraced 3d, because now it only works with grafixkart??? ? What am i doing wrong?
Please double check exactly which graphics card your friend is using and what driver he is running.
Then double check exactly which card you're using and check what driver is running for it.