Problem with smbpasswd

[redhatdude at bellsouth.net]

Hello,
I set up samba and added my user name w/ smbpasswd and there was no problems. I can connect to my samba share from MacOSX and Windows. However, I created a new user with useradd and when I try to set his smb password I get the following errors:

smbpasswd NewUser
New SMB password:
Retype new SMB password:
Failed to find entry for user NewUser.
Failed to modify password entry for user NewUser

What's going on here? How can I fix this?
Please help.
EJ