不存在的类:Mongo_db

我对ion_auth有问题。我转换了所有必需的文件适合Mongodb。我的配置莱尔斯mongo_db.php

<?
   $config['mongo_host'] = 'localhost';
   $config['mongo_port'] = 27017;
   $config['mongo_db'] = 'tls_saas';
   $config['mongo_user'] = 'root';
   $config['mongo_pass'] = 'root';
   $config['mongo_persist'] = TRUE;
   $config['mongo_persist_key'] = 'ci_mongo_persist';
   ?>

ion_auth.php

$config['use_mongodb'] = TRUE;
/*
| -------------------------------------------------------------------------
| MongoDB Collection.
| -------------------------------------------------------------------------
| Setup the mongodb docs using the following command:
| $ mongorestore sql/mongo
|
*/
$mongorestore                    = 'sql/mongo';
$config['collections']['users']          = 'users';
$config['collections']['groups']         = 'groups';
$config['collections']['login_attempts'] = 'login_attempts';

但我仍然收到错误

不存在的类：Mongo_db

是他们要做出更多的改变. ion_auth现在与MongoDB合作？？