When I switch mode from P to S or A,  I get a error message . Thanks

Give us a clue?  The error message is.............

you may not have the  setting to enable multi flight modes,    look thru the general settings menu i believe it is in the equipment menu.   change the setting to allow mult flight modes.     

more clues to your error would be very helpful but im just solving the easiest  and most common one with the lack of info.   hope this helps

I'm sorry, I could not remember the message. Flight modes is the answer. Thank you again.

If you read the manual they go over that issue.