C:\FSX\Scenery\World\scenery\KDM_LIRP_ADX_ALT.bgl
Is this the correct file and if not how do I find the correct file?
From the name, it looks like this is an altitude correction only AFCAD, so it's surely not the correct one, since they shouldn't contains any parkings but, apparently, for some reason, it seems this one contains at least one parking, because files with no parkings are automatically discarded by GSX.
However, an altitude correction file should have a very low priority in the Scenery Library. GSX of course respect the layer priority so, an higher layered file will always be chosen by preference against one for the same ICAO with a lower priority.
So, first thing you should check, is that this file stays on a lower priority layer in the Scenery Library, which is the proper place for an altitude correction .BGL.
However, if they made (very unusual) an altitude correction .BGL with a DIFFERENT ICAO, in order to represent in the same file another auxiliary airport, like a seaplane or an helipad, then you should check its ICAO, and EXCLUDE IT from GSX using the airport_visibility parameter, as explained in the GSX manual, Page 24.
If, instead, they made an altitude correction .BGL, using the same ICAO as the main one, added at least one parking (why???) and you are sure it's on a lower layer compared to the main one, then the only possible explanation why the correct one hasn't been used by GSX, is the correct one has some kind of problem.
A way to troubleshoot these issues is to enable Logging in the Troubleshooting page of the GSX Settings, and check the Couatl.LOG file that will be generated after you select the option to "Restart Couatl and rebuild the airport cache", it will surely explain why a particular .BGL has been rejected.
There's another thread here, again from an Aerosoft scenery:
http://www.fsdreamteam.com/forum/index.php/topic,15387.msg111508.html#msg111508The user reported the problem was fixed by reinstalling the scenery, which seems to indicate the main airport .BGL file was corrupted, so the problem never had anything to do with GSX.