samba - May 2004 - Awayse getting guest when trying to access share directory

I have installed samba and when I try to access the shared directory, the 
username promted is alwayse machine_name/guest I would like it to be one 
of the nis users on the server.

I added userneme = @user but this does not change anything, what am I 
doing wrong here ????


*********************************************************************************
Ce courriel ainsi que ses pieces jointes sont strictement reserves a
l'usage de la ou du destinataire et peut contenir de l'information
privilegiee et confidentielle. Si vous avez recu cette correspondance
par erreur, veuillez supprimer le message. Merci.

Ce courriel a ete verifie contre la presence de virus informatiques

This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom they
are addressed. If you have received this email in error please discard.

This email message has also been swept for the presence of computer viruses
**********************************************************************************