Hi,
this is the explanation:
in the first times of FlightLogger there was a rule saying that you can only fly an aircraft of the same class of the flight; during that the rules changed, but I didn't change the logic in FLLogger; the next release will solve that.
Meanwhile you can stick to the rules in the ops. manual and do not bother with the message that appears, as it's only purpose is to warn the pilot that there's possibly a mismatch between the the chosen flight's class and aircfraft's class.
Regards
Armando Chibante