哎，Cache又不行了， [ 新手入门 ]

Fatal error: Call to a member function get() on a non-object in $cache = Yii::app()->cache->get($key); 这行报错

'cache' => array(
          'class' => 'system.caching.CMemCache',
          'servers' => array(
               array('host' => '127.0.0.1',
                 'port' => 11211,
               ),
           ),
      	),

main.php文件里，