My extension cable was mis-wired in a completely different way - the ground was swapped with antenna control, preventing the module from working at all.

In short, if you have any kind of a problem with getting the tuner to work, the first thing is to check that the extension is wired straight through. If it isn't Support will send you another, or you can swap over the wires yourself if you prefer.

I don't believe this is a very widespread problem as it didn't show up in sample testing, but there are at least two confirmed cases so far..

Rob