No Flashers on tow dolly

[CWJK55]

Testing my tow dolly lights before leaving this morning I found that the lights worked for the turn signals and brakes but when I tried the emergency flashers the right (passenger side) light didn't come on. The left side flasher on the dolly and both on the motorhome worked fine.
I'm confused.

[Mr_D]

Had that problem, traced it to a bad ground. Fixed it and no more problems.

[CWJK55]

A bad ground was the answer. I was looking on the dolly, but the bad ground was on the four way plug coming out of the motorhome.
I still don't understand why it only affected the right side on the tow dolly.