hi i got a problem with pre listening for tracks

its not possible on my ddj 400 to prelisten a track without hearing the master i turn the headphone  mixing to cue and press cue on a channel but i always hear the master too ? if i turn the regulator to master i hear nothing ? if i press the cue button at the master level then i hear the master ?  but i cannot prelisten to a track on the phones alone ? thank you for your help...