Creating default object from empty value

Hello, when I am adding a new event to http://www.aparkforus.org/event-calendar, there is this warning at the top of the pop-up box:

Warning: Creating default object from empty value in /home/user-name/aparkforus.org/wp-content/plugins/ajax-event-calendar/inc/admin-event.php on line 25

I seem to be able to add the event and the warning is gone if I go back to edit the event. Is there something that I should do to fix this?

Thanks,

Jason

http://wordpress.org/extend/plugins/ajax-event-calendar/