Excluding stock scenery in FS9

Hi,I'm learning scenery editing and I'm quite new in this area.I'm using FSSC latest upgrade.There is this airport at my hometown, Orebro Airport (ESOE),I have excluded the surrounding grassfield at rwy 36/18 withuse of DefArea. That worked OK. But, problem is with excluding the semi transparent grass runway. It seems impossible to get rid of it. Also there's a polygon grass field on the west side of the runway that cannot be excluded. Interesting is that this area has no seasonal changes. It's just green in the winter.The same goes for the apron, I could exclude the misplaced buildings, but not the also misplaced apron.Any one having a solution for my problem?Thank'sLago