PFL with internal soundcard in version Pro 7.1

Hi, I'm testing the Pro 7.1 for mixing videos using Vestax VCI-100 rev.1 and as soundcard M-Audio Fast Track Pro or Vestax VAI-40, but I have the same problem. I can't use one channel of the sound card exclusively as PFL like in others mixing softwares.
I set one channel as monitor but it does'nt work.
I do something wrong?
It seems that all works correctly only using an external mixer.
Somebody can help me with the right setiings?
I set one channel as monitor but it does'nt work.
I do something wrong?
It seems that all works correctly only using an external mixer.
Somebody can help me with the right setiings?