Reply to Spin on Traktor using Mac

Hello,
I have this Vestax Spin hooked up with MacBook Pro 2010 Spring with Traktor in it, and it works fine thanks to mapping. But then monitoring or pre-cueing doesnt work... someone else said I should set 1 and 2 for monitoring and 3 and 4 for main output but it doesnt work either... any suggestions?
I want to be able to monitor each track using a headphone attached to Spin when I press headphone button on Spin, and main output to come out of Mac's speaker itself.

Thanks