diff --git a/pykolab/auth/ldap/__init__.py b/pykolab/auth/ldap/__init__.py
--- a/pykolab/auth/ldap/__init__.py
+++ b/pykolab/auth/ldap/__init__.py
@@ -246,6 +246,9 @@
                     level=8
                 )
 
+            # Remove referrals
+            _result_data = [_e for _e in _result_data if _e[0] is not None]
+
             if len(_result_data) == 1:
                 (entry_dn, entry_attrs) = _result_data[0]
 
diff --git a/wallace/module_resources.py b/wallace/module_resources.py
--- a/wallace/module_resources.py
+++ b/wallace/module_resources.py
@@ -432,6 +432,9 @@
 
     resource_dns = auth.find_resource('*')
 
+    # Remove referrals
+    resource_dns = [dn for dn in resource_dns if dn is not None]
+
     # filter by resource_base_dn
     resource_base_dn = conf.get('ldap', 'resource_base_dn', None)
     if resource_base_dn is not None: