[Samba] Adding a AD Group to a Unix user account

[James]

Hi Guys,

First of all I can do the following:

"usermod -g GID bobby" and it adds the group to the user account fine 
(GID being the actual number value not the name).

but if i don't use -g it fails to work, I want to ADD the group "Domain 
Users" to "bobbys" account, so I tried:

"usermod -a -G GID bobby" but it doesnt not appear to do anything...


Anyone got any ideas?

Many Thanks!

James