All right, so the transponder wasn't transponding. That is very, very unfortunate. Apparently the model/make of the transponder on board the legacy has a design flaw. And by that I do NOT mean the fact that it breaks down, as one can expect that all mechanical things go bust.
For some reason the bloody gadget can malfunction, and also not give some kind of warning that it is broken!!
If this is true, the manufacturer of this particular transponder must be feeling a bit uneasy by now, right?
What model/make of transponder is installed in the Legacy?