[Voyage-linux] setgid: Operation not permitted

[(spam-protected)]

Hi,

I've just create a new user for my voyage 0.7.5.
I want to use this, and only this user, for ssh login. I was about to disable the root login in the ssh config file when I've realized that from my new I cannot become root. 

myUser at machine:~$ su
Password: 
setgid: Operation not permitted
myUser at machine:~$ 

Do you know how can I avoid getting "setgid: Operation not permitted" ? 


Many thanks

Davide