hi cyriel
You need to check the aircraft.cfg located in the aircraft folder in this case I think it's called ehm_738. Open the aircraft.cfg with notepad or somethink like that and check that the radio part look like this
[Radios]
// Radio Type=availiable, standby frequency, has glide slope
Audio.1=1
Com.1=1, 0
Com.2=1, 0
Nav.1=1, 0, 1
Nav.2=1, 0, 0
Adf.1=1
Transponder.1=1
Marker.1=1
This thing with the radio is something you may run into more times. It's a good idea when you have installed a new aircraft to check this before you start flying.
Just like in the real world, it good to know you radio is working.
