RB67 Extension tube flash sync

I have a strange problem with one of my extension tubes. Namely, if I'm using my 82mm tube - my flash will not fire. It will work just fine with the 45mm, or with no tubes at all. Is this normal or could something be wrong with my tube?

Do any of your tubes have linkage for the iris for exposure control?

That shouldn't happen no matter what tube you use since the flash sync is in the lens, independant of the camera n tube.

The only thing I can say is perhaps the tube is not making a full revolution when firing the lens. Check to see if the tube pins rotate freely and complete the rotation when mounted on the camera body without a lens on it. Make a small tic with a pencil to see how far it goes compared with the plain lens mount rotation.