Works fine now.
I had to link Forum to Calendar. Its made in the Admin CP. In
vBulletin Options menu select
Event Forums and
Edit Settings.
Then enter your calendarid:forumid numbers to the Calendar/Forum Map text box.
I overlooked the Event Forums setting in vBulletin Options menu, thats why it was not working. This should be mentioned in the "How do I install it?" instructions maybe.
Anyway, this is a great plugin. Thanks.
I would appreciate the possibility to choose the arrangement of the thread title generated.