I'm new with this unit. I have an IPad Air. When I get the phantom 3 professional in the air about 30 feet I am in P mode. My lights are green, the GPS signal strength has full bars or usually a reading of 13 or more. When I switch to follow me and hit apply for the F mode a warning sign says signal strength is poor but all GPS indications still say I have excellent strength. What am I doing wrong as I have never been able to make this mode work. I have also tried my IPhone with the same results. Thanks for any help