I was working on an airport built as an AF2 airport for FS9. ADE loaded and saved an ADE file fine, but had schema errors on compile. The problem is parking spots with negative heading. Analysis shows that the problem spots, when opened in AFCAD2, show as -0.0. I guess AFCAD has no problem with this, but the bgl codes as values such as -0.00426948 which FS9 seems to have no problem with, but if you try to bglcompile it the schema won't allow (I suspect this is known but haven't figured out a good search query in the forum). Anyway the fix was to open the parking properties in ADE. ADE shows it as heading 0.0 and just clicking OK will save it as 0.0 which fixes it. I suppose there could be other circumstances where negative compass headings are created by AFCAD. scott s. .