When clicking an empty slot in the Garritan ARIA Player, you may see only the options "empty", "import", and "reload", with no instrument banks listed. Broken preference associations with the Garritan libraries, including Garritan Instruments for Finale, can cause them not to show up in the ARIA Player.
One of the more common causes of this is are multiple user accounts on the computer. Make sure you are using the most recent version of the ARIA Player on an administrator account. The best solution to correct this is to reinstall the library from the disk or download.
If the problem continues after reinstalling, contact Customer Success for assistance.