i had the firewall joined my domain "duktales.net". After i installed a new DC i named it
"mnt-IT.local" i had then left the old domain and joined the new domain.
!! I installed for webadmin a new certificate signed by the new DC. !!
After that i deinstalled and reinstalled the AAA, downloaded from the ASG.
Since that i get the error message showed in my first post.