It's no use checking if you have the bglman.dll file. You obviously have it, because the installer put it in there.
To know if it's RUNNING, you need to see if you have the Addon Manager menu inside FS9. If you have the bglman.dll file in the FS9\MODULES folder, and you don't see the Addon Manager menu, then it's an antivirus problem, and you need to explicitely say to the A/V to ignore the FS9\MODULES folder from scanning.
IF, instead, you SEE the Addon Manager menu, but you don't see the scenery, THEN it's NOTHING related to the Addon Manager at all, and you need to check your scenery.cfg, because it probably has some kind of error, so our installer don't touch it in these cases. If you can't fix your scenery.cfg, you can always add OHare manually in the Scenery Library, if this is the case.