Portlet throws the following error. Column "rivetlogic_event_Event.eventDate" is invalid in the ORDER BY

Hi, This portlet is very good. It gives all the flexible features that are not with Calendar CE portlet like No dependency with Private pages, Easy pages, upcoming events, not complex.
But there is a basic error exist in this portlet. Please fix it. As soon as i installed this portlet and click on Display event Portlet. It Gives the following error.
Column "rivetlogic_event_Event.eventDate" is invalid in the ORDER BY clause because it is not contained in either an aggregate function or the GROUP BY clause.