Linux as well but, er, actually, I think what you are having is normal since you are starting with "fgcom" only. Mine does the same.
You need to send it AD/freq values now, either:
- through UDP (made for programs like fgfs to enable moving and tuning);
- or manually from command line (see options with "fgcom --help").
Some help here :
http://wiki.flightgear.org/FGCom_3.0Check if you are connected on the live FGCom page, updated every few seconds :
http://fgcom.flightgear.org/If you have an ATC client working, you can try echo testing there; they handle the options for you.