I reinstalled the scenery, checked the scenery library, looked for another AFCAD. none worked. the first time ever i've seem a problem this similar. all my other fsdt/cloud9 sceneries work fine. this one no.
Since all the other fsdt/cloud9 sceneries works, I assume it's nothing related to the Addon Manager/activation or antivirus, otherwise you wouldn't see any of those sceneries.
This, of course, provided you are using the Addon Manager that comes with PHNL, which is the current version (since it's always automatically updated online), and you haven't manually replaced with an older version, because it will never work.
So, assuming you see the Addon Manager, it IS the current version, and the scenery appears on the Scenery Library (and it is on TOP of it, which is where the installer puts it by default), then the problem doesn' t have anything to do with our scenery, and it's something else in conflict.
Sorry but, an AFCAD it's not the only thing that can create this so, don't just discount the chance of another AFCAD being the problem, just because you haven't found any. The "another AFCAD in conflict" it's just the most common cause, but it's the only one. ANY scenery .BGL might be able to exlude another one so, you should check anything you installed.
Another thing to check, is your Autogen complexity slider and/or your Scenery Complexity slider: it shouldn't be set to "none", try to set it different levels, and see it if changes.