Dumb Rev2 question- Logic receives MIDI signal but no sound. Setup help please

I'm trying to figure out why I can't hear my Rev2 in Logic X. I set up an external midi track (set to Ch1) and paired it with an audio track, which was working the other day. I came back to use it tonight and can't get any sound. This is my first synth, so it's probably a user error, but Logic is very prone to give me trouble, so I'm not sure what to do. I've already restarted the program a handful of times.

Rev2 is plugged into my Mac via USB and a PnP device carrying the left and right output of MAIN/A OUTPUT. The tracks are record and monitor enabled. Rev2 is communicating because I can see it recognizing chords when I hold down multiple keys. I can get it to record/write midi, but it just won't play any new sounds, either live or playback. I can play the previously recorded track from the other day, but only it's audio track. It won't play the midi track.

I've been using Logic for a few years, but this is my first venture into the synth world, hence the newbie question! I just can't figure out what's different between the my previous session and now. Are there basic Rev2/LogicX settings that I should know about??

Thank you VERY VERY VERY much in advance. I'm pulling my hair out over here

update: the Rev2 works fine playing software instruments. I just can't get any synth sounds

I had that same problem in Cubase with my Kronos.  Make sure that Direct Monitoring for the audio track is turned on. It should be a button close to the arm and record buttons.

thanks! I'll double check that