The reasons for this message might be many:
- You might have forgot to Disable the GSX Jetway replacement file for that airport, which you should always do when installing a new airport. Failing to do so, will introduce a conflict, possibly resulting in that error.
- There might be another scenery in conflict, like a smaller airport nearby. Paris airports, for example, were both affected by the Asobo Voloport scenery, which had to be disabled to fix this problem.
- The scenery might really have a problem, like unconnected parking spots, orphaned nodes, missing links, etc. In this case, only the developer can fix it.