Hi, I have a problem getting more than one note at a time to play on the PSYN II synth. I have an organ synth selected and it can only play treble or bass cleff at a time. Any ideas what might be causing this?

Look at the polyphony on the bottom row.  If it is set to mono or 1 you will only hear one note at a time.  You can change the polyphony via the dial just right of the polyphony window.  You can change it from mono/1 to how every many notes you want to hear. For  example if you are only going to play triads change the mono/1 to three to hear all three triad notes.
 
I hope this helps.

I think that should do the trick, thanks!