3rd Output

Last night i was trying to configure the 3rd output of my soundcard and use it for my monitor but i could not find a way. Is there something that i am missing? I configure my outputs as usuall (1-2 master, 3-4 headphones and 5-6 monitor) but i didn't get any sound.
Thanks a lot
Stelios, Greece
Thanks a lot
Stelios, Greece