samba and virtual users

[redhatdude at bellsouth.net]

Hello,
Is it possible to create a smb user without having to create a system user for it?
Using the command smbpasswd -a NewUser fails with error: Failed to modify password entry for user NewUser.
I entered "encrypt password = yes" and "smb passwd file = /etc/samba/smbpasswd" in my smb.conf and still doesn't work.
Anyone knows the answer? Please help.
EJ