[aaquilato]

Yes.
The older Digi 192 has one analog input card, one analog output card and two digital i/o cards.

I also have an Apogee Trak 2 which has an Ambus HD card installed.

If I have everything connected, all the devices are seen in the i/o window, PT will launch but won't play. I get the -9129 error message.

If I have just the 192 connected the same scenario. PT sees both devices but will not play.

If only the Omni is connected, everything works perfectly.

Answering the question about clocking.
I have an Audio Design ProBox that is used to distribute clock to all my digital reverbs including a UA 2192.

I've tried using that as I normally would.
Omni to ProBox. ProBox distributes clock to 192, 2192, Trak 2, etc...
No go.

I've taken the PrBox out of the "proverbially loop" and connected using Loop Sync.
No go.

I've done this with both the 192 and the Trak 2 connected and with just the 192 connected.

Pro Tools will not play. As soon as I hit play I get the error message.

As soon as I disconnect everything Pro Tools plays.

AND connecting the Omni directly to the ProBox with the UA2192 connected as my D/A, Pro Tools plays.

It's only when I connect another i/o device that I get the -9129 error message.

What do you think?