Reply to problem with traktor LE and vci-100 crossfader

Hi!

I had a big problem with connecting Traktor LE and my vestax vci-100, but i reintalled traktor and now it work. But i still have some problem with the crossfader and the volume for both decks. It doesn't work at all. I can't switch track or pre-listen to tracks in my headphones. Do i need to midi mapp something? And how do i do then? I'm using mac os x and native instruments audio 2 soundcard..please help me.