Reply to Audio Kontrol 3/4 Outputs Not Working.

Yo yo.
BUILT THE STUDIO!
Have an audio kontrol running 4 outputs.
2 to Krk 8's, and 2 to Yamaha Hs50ms.
The 3/4 output won't work.
Using a macbook pro.
Set it up in system preferences, and the 1/2 outputs are working perfectly.
Suggestions?