Not found LDAP user with kerberos principal

[TiDirks]

Hey,

I am setting up a new keycloak instance.
After setting up the user federation, ldap Login is working fine, but the Kerberos integration keeps failing with the following error:
"Not found LDAP user with kerberos principal [username@domain]. Kerberos principal is [userPrincipalName]."
I also tried to leave the Kerberos principal empty, but the result remains the same.
I got an older version (6.0) running under the same configuration. Except for the value of Kerberos integration, which does not exist here.

Any ideas what I am missing here?

Thanks