setup problem with traktor 2

i have 2cdj 2000 and 2 cdj2000 nexus and djm 900 nexus. I am having problem getting the sound to work with traktor and what settings i should use. Should i be using the djm 900 as the soundcard ?? if I do that and set the settings on the mixer to usb on each channel it plays but i also get feedback and distortion. If i set the soundcard to cdj asio only 3 of the channels work the other channel plays sound from the pc and i have that set to cd/line ?? any help would be amazing

its fine i fixed the problem