TOPIC: SQL Error on Save New Event

An error has occurred.

1054 Unknown column 'c.ordering' in 'order clause' SQL=SELECT a. * FROM iqfg3_dtregister_group_event as a LEFT JOIN iqfg3_dtregister_categories as c ON a.category = c.categoryId order by c.ordering , a.dtstart desc , a.dtstarttime desc

I have the same issue, but only when save +close a new event. If I save a new event, all is OK. Here is the error displayed on screen:
Fatal error: Call to a member function get() on a non-object in /home/thetra73/public_html/administrator/templates/isis/error.php on line 114
and the error in the tab is:
Error:500SQL=SELECT a.*From jos_dtregister_group_event as a LEFT JOIN jos_dtregister_categories as c ON a.category = c.categoryId order by c.ordering, a.dtstart desc , a.dtstarttime desc

I opened a ticket a while ago for support and got a reply but no follow up.

At this point our company has lost business and valuable opportunity because of this issue.

WE CAN"T SELL TICKETS!!!

Please help!!!!!!!!!!!!!!!!!!!!!!!!!!!