Upgrade from a NW5.1 server to NW6.5 server and installed CIFS

When a user tries to browse to "Microsoft Windows network" the CIFS
server is not seen.

On another network where CIFS is installed on bot a NW6 and NW6.5
I can browse to the CIFS share on the NW6 server but can not see the NW6.5 share

What am I doing wrong?