orbitd on "[Plugin: All-in-One Event Calendar] 404 Error"

I am getting a 404 error for an event linked from the calendar - I've trashed and rebuilt the event post several times but no fix. It previews perfectly but when I publish, I get the 404 error. View at link below - May event 'Columbus Premier' - Thanks for your help - we are ready to promote this event but we can't due to this issue.

http://www.chambermusiccolumbus.org/calendar/

https://wordpress.org/plugins/all-in-one-event-calendar/