Forums Scripts & Popups User level.

Your level 999 is higher than 3. Users can access any events matching or less than their access level, noting that only the highest matching event is triggered.
on 3:event: <- This triggers for all users with a level of 3 or greater.
on +3:event <- triggers for ONLY users with level 3


Edit:
You can also prevent level 999 users from triggering it by adding their level at "=999" which gives that user access only to level 999 events.