Comment 10 for bug 791944

My huge mistake, sorry for making you loose your time. I use to do administrative tasks as root...

Here it goes:

root@kropotkin:~# /etc/init.d/nmbd start
Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service nmbd start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start nmbd
start: Job failed to start
root@kropotkin:~# service nmbd start
start: Job failed to start
root@kropotkin:~# cat /var/log/samba/log.nmbd
cat: /var/log/samba/log.nmbd: No such file or directory