Thanks for reply. Well I think, I tried that. Meanwhile I restarted Xplane. Frequencie change works well now. It's possible that I did something wrong, cause I'm a beginner using pilot2atc.
I've got a similar bug, if I dial in at EHAM Ground frequency 121.89 KHUJA Ctr is selected with 121.9 frequency, so I'm not able to ask for taxi instructions. I'm useing airac 1117.
Jens