There is a known issue in Finale 2012 updates on Windows where the Space Systems plug-in is incorrectly titled in the Plug-Ins menu.  To correct this, please follow these steps:

  1. Quit Finale 2012.
  2. Go to C:\ Program Files (x86 on 64-bit systems)\Finale 2012\Plug-ins\Scoring and Arranging.
  3. You should see a file here named SpaceSystems. Rename that file to spacesystems2.
  4. Relaunch Finale 2012.