I want to use my DP-24SD as a mixing board and a recorder. I'm new to the unit but I can't find anything in the manual. I've hooked the lines from my monitor plugs to the power amp. It works fine for playing the demo but I can't get it to play live through the board. When playing the demo all the track faders work, the stereo fader works and so does the monitor fader. What am I missing?