I did a flight from LKBT to LKKV this morning and something very strange happened. I was at 8.000ft. when I had to change the frequency to 123.0. The usual ATC window popped up with the option to tune to 123.0. I pushed the 1-key on my keyboard, but nothing happened, I changed the frequency myself on the radio, and again nothing happened. I reloaded the flight and the same problem occured, I then started the whole flight as a new one (meaning not reset flight), but once again the same problem occured.
The only non-standard FS-thingy in the neighbourhood of LKBT was an AFCAD, so to check if that was the problem I restored the default lay-out of the airport and tried again, sorry that I have to repeat this again, nothing happened.
So if anyone knows what this problem is or even better, how to fix it, I would appreciate your help.