Andrew,

Try going to MIDI/Audio > Audio Units Banks and Effects and see if the volume sliders for the used banks are set appropriately (meaning not set to 0). 

Thanks!

They are. And the master volume is at 100. I generally never mess with all that. I never got a firm understanding on the difference between SmartMusicSoftSynth and Garritan? (And Aria, for that matter.) When I reassign the voices on old charts, all the SmartMusic in the "device" column switches to Garritan. But in the banks, there is no Garritan option? Bank 1 is Aria, and bank 2 is SmartMusic...

The other thing is, I've been all over trying to find anything at all different between this piece and the one I worked on before or after, to see anything at all that is set differently, and I'll be darned if I can find anything...

Andrew, since this is document specific, use the Submit a Request button at the top to open a case with us. Attach the document to this and we can take a closer look on our end to see what could be happening here.

So I pulled up the original arrangement I had made years ago, and it plays (with SmartMusic sound.) So I went back to the problem arrangement, and when I select "Play through MIDI, it works! (not Garritan, but an improvement over silence.) I still can't figure out what goes wrong when I select "Play through audio units." Does that suggest a solution to anyone?

Thanks, this just showed up for some reason. I submitted it, thanks again!