cross dj - no sound through headphones

good day to you all,

thought about downloading cross dj for my hercules instinct and then i saw the trial version so went for that just to make sure everything is compatible. although i was initially pleased with the download (all seemed well... jog wheel, pitch bend, crossfader, tune selector all worked as anticipated) my pleasure soon diminished when i discovered that my headphones and associated buttons/switches on my hercules instinct failed to do what theyre supposed to do.

maybe im being a bit of dumb a##e, theres probably a simple answer and solution. does anyone have any ideas where im going wrong i.e.,  why i cant hear anything through my headphones??

if you have any advice i would be very grateful.

cheers peeps.