Problems with Kerberos and delegation account

ok makes sense - got a step further - I can resolve my webserver and dns works fine but this error tells me that I stil have "something" missing in the config:

Dec 18 13:47:29 bigip1 info websso.1[7758]: 014d0011:6: 5b4c38d9: Websso Kerberos authentication for user 'thomas' using config '/Common/KerbSSO' Dec 18 13:47:29 bigip1 debug websso.1[7758]: 014d0046:7: 5b4c38d9: adding item to WorkQueue Dec 18 13:47:29 bigip1 debug websso.1[7758]: 014d0018:7: sid:5b4c38d9 ctx:0x9bf8498 server address = ::ffff:192.168.12.20 Dec 18 13:47:33 bigip1 err websso.1[7758]: 014d0019:3: 5b4c38d9: Kerberos: Failed to resolve IP address: ::ffff:192.168.12.20 Dec 18 13:47:33 bigip1 err websso.1[7758]: 014d0048:3: 5b4c38d9: failure occurred when processing the work item

As far as I could see in the setup of the SSO I didn't need to change anything else here - the DNS server from the F5 is pointing to the DC and my domain name is equal to this realm (and if some reads the start of this question I wrote AAA serveres - this was a wrong term - it is the SSO I am fighting with since we have the serverside auth here) best regards /ti