Why can't I set up flights from some airports in Vietnam such as Lien Khuong (VVDL), Vinh (VVVH), Dong Hoi (VVDH)... I have moved the plane position there, can manually take off there but I can't make it part of the flight. I tried using FMC but it doesn't work, even the flights that appear in the flight schedule can't start.
