thin webserver don't start using "services"

Ubuntu 11.10

# service thin start
[start] /etc/thin1.8/pocztowka.yml ...

but it's missing, not running
# ps ax | grep thin
(empty)

now I start it by hand with my root account:

# thin start --all /etc/thin1.8
[start] /etc/thin1.8/pocztowka.yml ...
# ps ax | grep thin
 1652 ? Sl 0:01 thin server (127.0.0.1:3000)

as you can see now it's working, so this is not working only if I use "service" wrapper. don't know why is it so.