Iptables doesn’t log to /var/log/kern.log or syslog

iptables -A FORWARD -p tcp -j LOG --log-level debug
or 
iptables -A FORWARD -p tcp -j LOG --log-level info
or
iptables -A INPUT -p tcp -j LOG --log-prefix ' INPUT TCP ' --log-level 7

Doesn't log anything to kern.log or syslog at all. What might cause that and how to fix that?
Using Ubuntu 10.04.4 LTS

That's the contents of /etc/rsyslog.d/50-default.conf

#  Default rules for rsyslog.
#
#           For more information see rsyslog.conf(5) and /etc/rsyslog.conf

#
# First some standard log files.  Log by facility.
#
auth,authpriv.*         /var/log/auth.log
*.*;auth,authpriv.none      -/var/log/syslog
#cron.*             /var/log/cron.log
daemon.*            -/var/log/daemon.log
kern.*              -/var/log/kern.log
lpr.*               -/var/log/lpr.log
mail.*              -/var/log/mail.log
user.*              -/var/log/user.log

#
# Logging for the mail system.  Split it up so that
# it is easy to write scripts to parse these files.
#
mail.info           -/var/log/mail.info
mail.warn           -/var/log/mail.warn
mail.err            /var/log/mail.err

#
# Logging for INN news system.
#
news.crit           /var/log/news/news.crit
news.err            /var/log/news/news.err
news.notice         -/var/log/news/news.notice

#
# Some "catch-all" log files.
#
*.=debug;\
    auth,authpriv.none;\
    news.none;mail.none -/var/log/debug
*.=info;*.=notice;*.=warn;\
    auth,authpriv.none;\
    cron,daemon.none;\
    mail,news.none      -/var/log/messages

#
# Emergencies are sent to everybody logged in.
#
*.emerg             *

#
# I like to have messages displayed on the console, but only on a virtual
# console I usually leave idle.
#
#daemon,mail.*;\
#   news.=crit;news.=err;news.=notice;\
#   *.=debug;*.=info;\
#   *.=notice;*.=warn   /dev/tty8

# The named pipe /dev/xconsole is for the `xconsole' utility.  To use it,
# you must invoke `xconsole' with the `-file' option:
# 
#    $ xconsole -file /dev/xconsole [...]
#
# NOTE: adjust the list below, or you'll go crazy if you have a reasonably
#      busy site..
#
daemon.*;mail.*;\
    news.err;\
    *.=debug;*.=info;\
    *.=notice;*.=warn   |/dev/xconsole