--- a/mod_lib_ldap/ldap.lib.lua	Mon Dec 10 22:15:27 2012 +0100
+++ b/mod_lib_ldap/ldap.lib.lua	Mon Dec 10 22:16:18 2012 +0100
@@ -188,6 +188,9 @@
     if who then
         who = who.dn;
         module:log('debug', '_M.bind - who: %s', who);
+    else
+        module:log('debug', '_M.bind - no DN found for username = %s', username);
+        return nil, format('no DN found for username = %s', username);
     end
 
     local conn, err = ldap.open_simple(params.hostname, who, password, params.use_tls);