When setting the cruise altitude for a route to 1500 ft, I get an error message telling me that the airplane power is not sufficient for flying the route as planned. (The exact message is "Die Flugzeugleistung ist nicht ausreichend, um die Route wie geplant zu fliegen." because I have the German version.) The message appears for all of my airplanes and only for 1500 ft.

I don't know why this happens. The cruise performance for MSL and for 2000 ft is configured, as well as the climb power for MSL and ceiling altitude. Does anybody have an idea?

Kind regards