Samba Configuration Question

I cannot get "valid users = <username>" to work.

I have two Linux Ubuntu servers, one 12.04, and the other one 14.04, both running Samba.,

The 14.04 system lets me add the parameter "valid users" to the share configuration in the smb.conf file. Only the windows7 machine with the matching logon name as on the Ubuntu Samba server will allow access to the share. This works just as advertised and expected

However, on the other Samba server that is running under Ubuntu 12.04, if I add the "valid users" parameter to the share configuration, the windows7 system will deny access to the share.

I thought I understood this. It was working. But, I found after the windows7 system rebooted, all the shares from this windows system work as expected except this 12.04 Samba server. If I remove the "valid users" statement, access is granted.

This is what I understand:

I MUST have a windows 7 logon name, let's say "ray". "ray" must have a passwrod.
I MUST have a Linux user named "ray" with the same password as the Windows7 user.
I MUST have a samba user name "ray" with the same Samba password as Windows and Linux.

This is what I have on both Samba servers. The file permissions on both Samba servers are identical.

Please tell me what I am missing?