install printer failed authentication (fetching device list) password fails

I installed Ubuntu for some days ago. This was not easy. It seems to work now.
But I cannot install my printer.
Ubuntu does not recognize the printer automatically.
When I press 'add printer' the autentication (fetching device list) appears. But username and password donot work: I cannot get any further.
The printer is a Brother HL-1450, connected via LPT.
I red some commands on the net, but it didnot get me further (I donot understand the meaning of the commands).
Here is the answers I got:

xx@localhost:~$ sudo su
[sudo] password for xx:
root@localhost:/home/xx# tail -f /var/log/messages
tail: cannot open `/var/log/messages' for reading: No such file or directory
root@localhost:/home/xx# ls -l /var/log
total 5060
-rw-r--r-- 1 root root 26997 Jun 4 19:39 alternatives.log
-rw-r----- 1 root adm 0 Jun 3 11:20 apport.log
-rw-r----- 1 root adm 873 Jun 3 00:35 apport.log.1
drwxr-xr-x 2 root root 4096 Jun 2 10:22 apt
-rw-r----- 1 syslog adm 22102 Jun 4 22:31 auth.log
-rw-r----- 1 syslog adm 132363 Jun 3 11:17 auth.log.1
-rw-r----- 1 root adm 31 Apr 23 13:35 boot
-rw-r--r-- 1 root root 1971 Jun 4 19:44 boot.log
-rw-r--r-- 1 root root 46891 Apr 23 13:35 bootstrap.log
-rw-rw---- 1 root utmp 4224 Jun 2 18:13 btmp
drwxr-xr-x 2 root root 4096 May 31 23:07 ConsoleKit
drwxr-xr-x 2 root root 4096 Jun 4 19:28 cups
drwxr-xr-x 2 root root 4096 Apr 20 19:23 dist-upgrade
-rw-r----- 1 root adm 40669 Jun 4 19:44 dmesg
-rw-r----- 1 root adm 41395 Jun 4 19:01 dmesg.0
-rw-r----- 1 root adm 12338 Jun 3 20:18 dmesg.1.gz
-rw-r----- 1 root adm 12102 Jun 3 17:53 dmesg.2.gz
-rw-r----- 1 root adm 12229 Jun 3 10:53 dmesg.3.gz
-rw-r----- 1 root adm 12205 Jun 2 22:39 dmesg.4.gz
-rw-r--r-- 1 root root 1175541 Jun 4 19:39 dpkg.log
-rw-r--r-- 1 root root 24072 Jun 2 18:16 faillog
-rw-r--r-- 1 root root 2652 Jun 2 10:37 fontconfig.log
drwxr-xr-x 2 root root 4096 Apr 23 13:35 fsck
drwxr-xr-x 2 root root 4096 Apr 4 14:18 hp
-rw-r--r-- 1 root root 0 Jun 2 10:45 jockey.log
-rw-r--r-- 1 root root 26852 Jun 2 10:45 jockey.log.1
-rw-r----- 1 syslog adm 259996 Jun 4 22:09 kern.log
-rw-r----- 1 syslog adm 1456481 Jun 3 10:53 kern.log.1
-rw-rw-r-- 1 root utmp 292876 Jun 2 18:16 lastlog
drwxr-xr-x 2 root root 4096 Jun 4 19:44 lightdm
-rw-r----- 1 syslog adm 0 May 31 23:05 mail.err
-rw-r----- 1 syslog adm 0 May 31 23:05 mail.log
drwxr-xr-x 2 root root 4096 May 31 23:05 news
-rw-r--r-- 1 root root 86512 Jun 4 19:45 pm-powersave.log
-rw-r--r-- 1 root root 15996 Jun 1 18:27 pm-suspend.log
drwxr-x--- 2 root adm 4096 Apr 12 22:11 samba
drwx------ 2 speech-dispatcher root 4096 Feb 6 03:51 speech-dispatcher
-rw-r----- 1 syslog adm 104780 Jun 4 22:25 syslog
-rw-r----- 1 syslog adm 303328 Jun 4 19:28 syslog.1
-rw-r----- 1 syslog adm 165441 Jun 3 11:20 syslog.2.gz
-rw-r----- 1 syslog adm 219162 Jun 2 10:45 syslog.3.gz
-rw-r--r-- 1 root root 231264 Jun 4 19:44 udev
-rw-r----- 1 syslog adm 0 May 31 23:05 ufw.log
drwxr-xr-x 2 root root 4096 Mar 12 10:03 unattended-upgrades
drwxr-xr-x 2 root root 4096 Jun 4 19:44 upstart
-rw-rw-r-- 1 root utmp 178944 Jun 4 22:31 wtmp
-rw-r--r-- 1 root root 51303 Jun 4 20:00 Xorg.0.log
-rw-r--r-- 1 root root 52493 Jun 4 19:43 Xorg.0.log.old
-rw-r--r-- 1 root root 51174 Jun 3 12:42 Xorg.1.log
-rw-r--r-- 1 root root 51173 Jun 2 23:44 Xorg.1.log.old
-rw-r--r-- 1 root root 43284 Jun 3 00:41 Xorg.2.log
-rw-r--r-- 1 root root 48339 Jun 2 16:29 Xorg.2.log.old
-rw-r--r-- 1 root root 43284 Jun 2 18:18 Xorg.3.log
-rw-r--r-- 1 root root 50345 Jun 2 18:18 Xorg.3.log.old
root@localhost:/home/xx# tail -f /var/log/syslog
Jun 4 22:09:13 localhost kernel: [ 8692.857428] audit_printk_skb: 21 callbacks suppressed
Jun 4 22:09:13 localhost kernel: [ 8692.857444] type=1400 audit(1338840553.011:27): apparmor="DENIED" operation="file_lock" parent=1 profile="/usr/sbin/cupsd" name="/run/utmp" pid=534 comm="cupsd" requested_mask="k" denied_mask="k" fsuid=0 ouid=0
Jun 4 22:09:15 localhost kernel: [ 8694.880497] type=1400 audit(1338840555.035:28): apparmor="DENIED" operation="file_lock" parent=1 profile="/usr/sbin/cupsd" name="/run/utmp" pid=534 comm="cupsd" requested_mask="k" denied_mask="k" fsuid=0 ouid=0
Jun 4 22:17:02 localhost CRON[2333]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Jun 4 22:20:19 localhost dhclient: DHCPREQUEST of 192.168.1.216 on eth1 to 192.168.1.1 port 67
Jun 4 22:20:19 localhost dhclient: DHCPACK of 192.168.1.216 from 192.168.1.1
Jun 4 22:20:20 localhost dhclient: bound to 192.168.1.216 -- renewal in 1562 seconds.
Jun 4 22:25:41 localhost dhclient: DHCPREQUEST of 192.168.1.132 on eth0 to 192.168.1.1 port 67
Jun 4 22:25:41 localhost dhclient: DHCPACK of 192.168.1.132 from 192.168.1.1
Jun 4 22:25:41 localhost dhclient: bound to 192.168.1.132 -- renewal in 1472 seconds.

tail -f /var/log/dmesg
Jun 4 22:46:23 localhost dhclient: DHCPREQUEST of 192.168.1.216 on eth1 to 192.168.1.1 port 67
Jun 4 22:46:23 localhost dhclient: DHCPACK of 192.168.1.216 from 192.168.1.1
Jun 4 22:46:24 localhost dhclient: bound to 192.168.1.216 -- renewal in 1560 seconds.
Jun 4 22:50:13 localhost dhclient: DHCPREQUEST of 192.168.1.132 on eth0 to 192.168.1.1 port 67
Jun 4 22:50:13 localhost dhclient: DHCPACK of 192.168.1.132 from 192.168.1.1
Jun 4 22:50:15 localhost dhclient: bound to 192.168.1.132 -- renewal in 1404 seconds.