[Samba] smbpasswd fails

[Chris Smith]

Trying to use smbpasswd to change a password and I get:

Old SMB password:
New SMB password:
Retype new SMB password:
SAMR connection to machine NT_STATUS_ACCESS_DENIED failed. Error was
127.0.0.1, but LANMAN password changed are disabled

This is with samba-3.5.2.

Any clues?

Thanks,

Chris