When I tried to follow your link, I got this message:
TomK, you do not have permission to access this page. This could be due to one of several reasons:
1.Your user account may not have sufficient privileges to access this page. Are you trying to edit someone else's post, access administrative features or some other privileged system?
2.If you are trying to post, the administrator may have disabled your account, or it may be awaiting activation.
Maybe only Administrators can add to the calendar (and have an "Add Event" button displayed)? Could be why no one uses it...