I'm pretty sure you'll have to put quotes around your group name:
valid users = "@DOMAIN+# All Users / FCC"
If you are using 'services for unix' on a windows box, you're best bet is to map users to unix user names and also map your groups to unix groups. It's been a while for me but I believe there is a button for this AND I believe it will tell you that it will start an NIS service. That means you will have to setup your unix machine to talk to your windows machine via nis.
So the group above could be mapped to the unix group called: all_fcc_users
Then in your smb.conf file you can change the valid users line to:
valid users = @all_fcc_users
Last edited by tonyfreeman; 12-21-2012 at 10:42 PM.
Reason: added iinfo about services for unix