Exclude certain event category from the loop

Hey there, great plug-in you made.

One question though, events I add show up in my custom loop, like I want it to be, however, I’d like to exclude some of the events from the loop. I tried adding a category like ‘CONCEPT’ to these events, but I cannot seem to be able to exclude these events during the loop using get_cat_ID and cat__not_in or cat=-.

Any thoughts on how to do this?

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