Some Questions about Airport v3 and senery items

[flipper_tech]

I have started designing some heliports using Airport v3 but I am having trouble getting the helipads and taxiways to show up.
Instead of getting the .BMP image I chose I am getting a white patch in the shape of the helipad or taxiway. I'm sure I am missing something simple, but I can't figure it out. I am using BMPs which already used in FS2k2 pro and have tried placing the ones I use in the texture folder of my addon as well as the standard texture folder.

In my test project I tried creating a rooftop heliport with multiple parking spaces and taxiways. Is there a way to raise the taxiways and the AFCAD maps to rooftop level.

Thanks in advance