As downloaded, the C90B Nav or COM radios would not change frequency in the panel view or the pop up radios view. The solution that worked for me was to revise the [radios] section of the C90B aircraft.cfg to all the same [radios] entries that are used on the FS2004 default King Air 350 aircraft.cfg [radios] section. Then revise the C90B [radios] entry to delete the ADF.2 line, since the C90B has only one ADF. Apparantly, the problem was that the downloaded [radios] section of the C90B has entries for NAV.1 and COM.1 that enable standby frequencies. The radio gauge(s) used in the C90B Ver 3 do not have standby frequency capability, and that locked up the simulation's ability to change NAV.1 or COM.1 frequency.