GarageBand 11 won't play all the notes!

I am a proud owner of a MacBook Air '12. However, I had to get a new hard drive recently. I downloaded GB '13, but didn't like it overall. I copied GB '11 off my TimeMachine, and put all the instruments in App Support.

However, since I did that, all the legacy analog synths except Analog Mono have a problem. Only one note will play at a time through the "monitor" in GB '11. When I record, it will play two or three notes, but cut out the first notes with each new note that I hit after three. And all the GB '13 synths (including the pads) only play one note at a time, in the same way.

When I play back the recording, all the notes I played are there, so it's not a problem with my MIDI controller. I would appreciate any help!