MP Flight Modes error setting parameter

Hi everyone! I need help! APM 2.8 with latest possible firmware, remote controle Flysky FS-T6 and modification with 3 position auxiliary key for Flight Modes. Trying to send parameters to ardupilot was unsuccessful! MP gived me message error setting parameter"? I understand that this board is not already supported but would be very appreciate if someone helps!

Get a version of Mission Planner which is coming from the same period as your firmware. I would say it is around 1.30, but check release dates.
You can download archived versions of MP from here https://firmware.ardupilot.org/Tools/MissionPlanner/archive/

Thanks!This is good idea! The same passed trough my mind and later today I’ll try!

I forgot to say that message appeared on Flight Modes menu!

So this problem was solved writing the necessary parameters directly in full parameters list and saving! Double checked after that with disconecting power supply and restarting mission planner and is OK!

INdeed, full parameter list is always working, regardless of MP/Controller version.