[Samba] smbpasswd doesn't work for users

[Ulf Rasch]

Hello list,

I have a problem with users changing their password from the command 
line of the localhost with smbpasswd.
As root the whole thing works fine but not as a normal user.
First I had the connection to the localhost refused because I didn't 
list localhost at the  interfaces and had "bind interfaces only" set to 
  yes. (manual smb.conf) I fixed that and added localhost.
Now I can connect to the localhost from the command line e.g. with 
smbclient but smbpasswd still doesn't work as expected.

user at host:~> smbpasswd
Old SMB password:
New SMB password:
Retype new SMB password:
machine 127.0.0.1 rejected the (anonymous) password change: Error was : 
Password restriction.
Failed to change password for user

Where do I have to configure the password restriction?
I can post my smb.conf if that would be of any help.
Any hint would be really helpful.

Thanks

Ulf