I found in the FAQ
"When i click on an event in the graphical calendar nothing happens
Make sure you set up the page for the single event view. If this is not set up, nothing will happen when clicking on an event.".
After installation of wp calender i deleted the 'Page' that is created(?) with installation. In de setting of the widget i choose antoher Page to set up for single event view. That Page is highlited as in the documentation is shown.
But hat page has a permalink which is not correct i think; can that be the cause of the problem?
If so how can i resolve which permalink i should use or is there a way to make the default page that is created upon installation again?