Hi Antonio
I had the same problem on our Server. The solution is *not* to use the samba configuration tool from fedora. Use swat instead. (http://servername:901 in your favourite browser)
I believe the tool from RH has problems to set the server role accuratly. You can safely use the tool to set up the samba users. It worked for me, but please don't touch the "server role" ;-)
I hope it helps
Olaf
