Anybody out there with the TC-80N3 remote timer?

Hi all.

I'm trying to troubleshoot a frequent problem I'm having with this thing: Often, the camera will only fire on every OTHER increment. So, if the timer's set to fire every three seconds, the camera takes a shot only every six.

It's not caused by the inability to write to the CF card fast enough, because if I trigger the shutter manually, I can fire it off at the desired interval indefinitely.

Also, the camera is on manual focus, so it's not a case where the camera refuses to fire because of failure to acquire focus.

Anybody else see this?

Thanks!