As explained so many times on the forum, no buildings does NOT mean "Trial expired", unless you mean "no buildings after 5 minutes".
Does the scenery works for the first 5 minutes ? If yes, it means you have an activation problem, so the scenery is still in Trial. If no, it means your problem doesn't have anything to do with activation, and it's just the software not running correctly or, possibly, either the scenery or the airport not using the latest version.
Be sure you install with the antivirus disabled and, after installing, configure it to exclude the whole FS9 folder from scanning.