The Ninja OBC communicates with the aircraft to be able to transmit and receive messages from Map Pilot. This communication can not occur if the remote is not in proper position.
IMPORTANT: Make sure that the remote is on and is in the programmed flight mode (F on PAF switches, P on PSA switches) before the aircraft is powered. It takes about 30 seconds for the controls software to start and if the remote isn't in the correct mode it will fail to communicate with the aircraft.
This applies to Agronaut and triggering variants of the Ninja.
If there is an issue with the communications the following message will be displayed and the aircraft will not be able to take off.