Samba users cannot change their own passwords. The password can only be changed using root account using the command

smbpasswd -a <username>

But I want users be able to change their passwords by their own. When password is tried to changed using a non-root account I get the below error message.

$ smbpasswd
Old SMB password:
New SMB password:
Retype new SMB password:
Could not connect to machine 127.0.0.1: NT_STATUS_LOGON_FAILURE
Failed to change password for user1

Any reasons for this? How can I fix this?