The following related log entries are found: 2015-01-28T10:12:57.560642+01:00 dhcp-254-32 pamtester: pam_unix(thinlinc:auth): check pass; user unknown 2015-01-28T10:12:57.561487+01:00 dhcp-254-32 pamtester: pam_unix(thinlinc:auth): authentication failure; logname= uid=0 euid=0 tty= ruser= rhost= Running pamtester with same arguments as webaccess, successfully completes as expected. I also verified that all pam conversation strings hasn't changed.
The problem was simply that the wrong username was used. Now works with both Henriks and my installation.