No 3D structures

Am having a big problem with the Land class Layer. I was working on an airport (MGPB) and after one compilation the Landclass layer was "Flat", no 3d structures. I have deleted the BGL but now I do not get the original 3d land class as it was on the original fsx . . The only thing I can see messing things up is that I used Airport Wizard to change the lights and add some other lights, other than that I just followed the regular steps to compile the Bgl, so the airport is messed up.. I worked on another airport before this one and everything there is fine. Can someone give me a clues what happened??​