Worked fine before now it won't.

1. Set Studio One Audio to XUSB
2. connected Mac Book Pro to Behringer Mixer via USB
3. eDrums connected into Behringer
4. Audio out from Mac Book into Roland via mix in.

1. I have prerecorded the band on multiple tracks.
2. I can see the volume indicators showing sound coming out of S1
3. Behringer is seeing the sound coming out of S1 (via the USB)
4. I can hear the drums. (earphones from Roland)
5 I cannot hear the prerecorded tracks I want to lay down a drum track for.

This set up worked fine until last night and then it stopped.
Normally I unmute all other instruments, hit the record button on the drum and I can hear the other instruments, and the drum, and watch the drum beat record.

There must be an easy fix because it just stopped when I was screwing with it. But for the life of me I cannot find my problem.

Any suggestions?