you have a number of problems in the way this is set up.
your form should be set to post to the kontakt.php
the validation and UE behavors should only be on the kontakt.php page, you have them on the kontakt fel.php page as well
in the server validation on the kontakt page, set the failed redirect to the kontakt fel.php page (This is already done)
in the UE behavior on the kontakt.php page set the Go TO to go to the thank you page (this is also already done)