FX on DDJ SX – No Sound Manipulation

my FX are not working. I have the channel FX assignments set, I have turned on the FX with the button below the knob (and turned it) – still no change. the lights come on and the knobs are responsive on Serato DJ, but the sound doesn't change. Please respond.

I am quite unhappy considering I paid good money for this controller. Is this a bug with Serato DJ or an issue with the controller itself?