How do I configure smb.conf file so that failed user login attempts will get logged into the samba logs?

Issue

• How do I configure smb.conf file so that failed user login attempts will get logged into the samba logs?
• Why failed user login attempts are not getting logged in samba logs?
• for example:

[2014/11/08 10:22:40.604819,  2] auth/auth.c:304(check_ntlm_password)
  check_ntlm_password:  authentication for user [xxx.yyy] -> [xxx.yyy] -> [xxx.yyy] succeeded

[2014/11/08 10:25:40.604913,  2] auth/auth.c:314(check_ntlm_password)
  check_ntlm_password:  Authentication for user [xxx.yyy] -> [xxx.yyy] FAILED with error NT_STATUS_WRONG_PASSWORD