Modify windows ad password

[Yuan-Chung Hsiao]

Hi

I use python-ldap(2.3.8) to modify AD's user password.
When I run it, the password change done, it always show traceback message.

Traceback (most recent call last):
  File "ldapauth.py", line 141, in <module>
    modifyAD('userid','passwordblah')
  File "ldapauth.py", line 105, in modifyAD
    conn.modify_s(dn, attr)
  File "c:\lang\python\lib\site-packages\ldap\ldapobject.py", line
327, in modify_s
    msgid = self.modify(dn,modlist)
  File "c:\lang\python\lib\site-packages\ldap\ldapobject.py", line
324, in modify
    return self.modify_ext(dn,modlist,None,None)
  File "c:\lang\python\lib\site-packages\ldap\ldapobject.py", line
297, in modify_ext
    return self._ldap_call(self._l.modify_ext,dn,modlist,EncodeControlTuples(serverctrls),EncodeControlTuples(clientctrls))
  File "c:\lang\python\lib\site-packages\ldap\ldapobject.py", line 96,
in _ldap_call
    result = func(*args,**kwargs)
TypeError: argument 1 must be string, not None

snippets code:
def modifyAD(username, password):
  LDAP_SERVER = 'ldaps://myad:636'
  LDAP_ADMIN = admin at myad'
  LDAP_PASSWD = ''
  BASE_DN = ''
  searchScope = ldap.SCOPE_SUBTREE
  conn = ldap.initialize(LDAP_SERVER)
  ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, '-ad.pem')
  ldap.set_option(ldap.OPT_REFERRALS,0)
  conn.protocol_version = ldap.VERSION3
  conn.bind_s(LDAP_ADMIN, LDAP_PASSWD)
  searchFilter = 'cn='+username
  attrs = ['unicodePwd']
  ldap_result_id = conn.search_s(BASE_DN, searchScope, searchFilter, attrs)
  if (ldap_result_id == []):
    print 'user not found'
  else:
    newPassword = ('"%s"' % password).encode('utf-16-le')
    for dn,entry in ldap_result_id:
      attr = [( ldap.MOD_REPLACE, 'unicodePwd', newPassword)]
      try:
        conn.modify_s(dn, attr)
      except ldap.LDAPError, error:
        print 'error',error
  conn.unbind_s()


Does anybody known how to solve?

Best regards,
ychsiao