Strange chkconfig behaviour on Debian for samba service

The service "samba" is not starting at boot on this standard Debian 7.7 installation while it should.

Based on the chkconfig man page, I did this, but it still doesn't start at boot :

chkconfig samba 2345

If I compare to the ssh services it looks good :

chkconfig --list|grep "ssh\|samba "
samba                     0:off  1:off  2:on   3:on   4:on   5:on   6:off
ssh                       0:off  1:off  2:on   3:on   4:on   5:on   6:off

But something else looks strange (all services are "on", only samba is "2345") ?

# chkconfig |grep "ssh\|samba "
samba                   2345
ssh                     on

Then I tried something else :

# chkconfig samba on

But this is clearly worse :

# chkconfig --list|grep "ssh\|samba "
samba                     0:off  1:off  2:off  3:off  4:off  5:off  6:off
ssh                       0:off  1:off  2:on   3:on   4:on   5:on   6:off
# chkconfig |grep "ssh\|samba "
samba                   off
ssh                     on

At this point I'm really confused, I tried to follow all manpages, forums and documentation and nothing the configuration is not behaving as expected. Am I missing some obvious point ?

Thanks a lot for any help !

P. S. In the above quotes, I'm always comparing to SSH because this service is working.

P. P. S. Update for the first comment, I also tried that :

# update-rc.d samba enable 2
update-rc.d: using dependency based boot sequencing
update-rc.d: error: no runlevel symlinks to modify, aborting!