If you see the default buildings mixed with the FSDT buildings, it means you have another AFCAD in conflict from another product. If the airport scanner couldn't find a conflicting AFCAD, it might be caused by a non-AFCAD scenery, and those are not found by that program, so you must remove them yourself.
This, of course, assumes you have KLAX on top of the Scenery Library, which is where the installer puts it by default. If you move it down, anything can happen, so you must put it back were the installer puts it.