Troubleshoot my system

[Grog12]

Here is a recent problem I have had and fixed. Students tell me what's wrong, how its causing my issue and how to fix it.

I run a theatre with a 48/96 Express with a 96 ETC Sensor dimmer rack, we also run Unison

The show that is currently renting my space has provided their own dimmers, movers, hazers and generator for the show. They would like control of houselights from their grand-MA on pc (with the widget). They only have one universe so they're running off a Opto/Iso. We run DMX from their hazer to the DMX input onstage and repatch my racks to start at 301.

We can control house lights from my board, but not theirs. The hazer won't respond when we patch our system into theirs. They have correctly patched their board.

What's wrong?

 

[Morpheus]

Well, my first thought was a bad opto-splitter, but I think not if two different lines "went down" depending on the control surface patched in...
The only other things I could think of are
a) both boards patched in at the same time (probably not)
b) Something about that hazer cable sounds off... is it a problem with installed wiring?