Rotax 582 Tach Problem

I've got about 200 hours on my Rotax 582 engine and was flying one day
when the tach quit. I bought a new Westach tach and installed it.
When I started the engine the tach seemed to work just fine but then
after a couple of minutes it quit. Thinking that I had a defective new
tach I sent it back and got a new one. I installed the new one and the
same problem. During the whole time the engine is running fine, I just
don't have the tach working. Has anyone else had this problem? If so
what was the solution? Thanks in advance for any help.

George