You don't say what airplane you are referring to with "My A320". If it's a supported plane, be sure you use the configuration that comes with GSX, and not something you made/downloaded yourself in the past.
To do that, check the airplane configuration page in GSX, and read from where GSX is taking the configuration data from. If it's not from the internal database (assuming you are using a supported A320), use the RESET button to revert to the configuration that comes with GSX.
If, instead, the airplane is not supported, and you are using a configuration you made yourself, be sure you assign the doors correctly.