need help, IMac to dCS Puccini word clock

I just disassembled my system to put it in a new rack, and cant get it back owrking. I used an IMac as a server, with a USB connection to a dCS external word clock, which in turn is connected to a dCS Puccini CD player.

I know I have everything downstream form the CD player hooked up correctly because I can play CDs from the CD player to the preamp.

I think the issue is in the IMac midi set up-- icalled Apple and they were befuddled...can anyone help me make sure the IMac is configured correctly to send the data stream to the clock vis I tunes?

Thanks

Mitch