From your reply, it seems that you haven't read the GSX manual. GSX has its own configuration for doors, the aircraft.cfg is only used when there's configuration at all for GSX, just as a very rough starting point but, in order to use an airplane, you must configure it with the airplane configuration editor included with GSX.
This will produce a GSX.CFG file in your %APPDATA%\Virtuali\Airplanes folder but, you are really not supposed to edit it manually, since the GSX editor is visual as so much easier to work with, compared to editing files.
I really suggest having a look at the GSX manual, starting at Page 35, where airplane customization is discussed.