Reply to Problem running Traktor, mixer not working please help!

Hi there, i'm new to these community s, mixing and traktor so my knowledge is low on all of this stuff but any help would be really appreciated,
I have a problem with my mixer not working within traktor.. my setup is 2x Technics, and a Numark M3 mixer, I have Traktor Scratch A6.
I can run Traktor fine and the turntables work and play the music through correctly, just as soon as i try to use my crossfader or volume controls on my mixer nothing happens and both tracks continue to play at the same volume.
I've selected external mixing and i believe everything is as it should be, i'll put screenshots up anyway...
All my RCA leads are connected correctly too.
The other problem I have is not being able to hear any sound except through the headphone part of my mixer, i can't seem to set up my speakers, connected to my PC with a jack-jack lead to play the music.
Any help really appreciated !!!
Nick.