Again me because of my previous problem not beeing able to submit events anymore...
What else I noticed is that the Code in the PHP file looks as follows:
<form name="new_event" action="<? $_SERVER['PHP_SELF'] ?>?page_id=<?= $page_id?>" method="post">
But when I have a look at the generated source, it looks a bit different:
<form name="new_event" action="?page_id=8" method="post">
Seems as if some variables could not be resolved, could this have an impact on my problem? Does anyone have an idea or any hint how to test this? When I submit the form I'm taken back to the page overview...