Some DMX-512 equipment have pins 2 and 3 wired in reverse order compared to official standard.
Check the manuals to see if this is the case.
If your case is this, then build a small adapter cable that crosses wires going to pins 2-3 and then conencts pin1 straight trough. Connect this adapter cable to the non-compliant equipment to make it up to the standard.

Wrong DMX-512 signal polarity can lead to thigns not working at all (do nothing) or the equipment connected making something strange because that they get in is complete carbage to them (different equipment might mis-interpred them differently).