php – CodeIgniter HMVC扩展了MX_Controller,无法正确使用get_i

/application/core/CMS_Controller.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

require APPPATH."third_party/MX/Controller.php";

class CMS_Controller extends MX_Controller {

    public function __construct() {
        parent::__construct();
    }

    public function show_something() {
        echo "something shown";
    }
}

我在模块中有另一个控制器(/modules/my_module/controllers/controller.php),它从CMS_Controller扩展而来

/modules/my_module/controllers/controller.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

class Controller extends CMS_Controller {

    public function index() {
        $this->load->view('view');
    }
}

并且,在view.php(/modules/my_module/views/view.php)中我这样做：
/modules/my_module/views/view.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
 $ci =& get_instance();
 echo $ci->show_something();
?>

我收到这个错误：

Fatal error: Call to undefined method CI::show_something() in
/home/gofrendi/public_html/No-CMS/modules/my_module/views/view.php on
line 3

如果我不使用MX_Controller并使用CI_Controller,它将起作用：
/application/core/CMS_Controller.php

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

//require APPPATH."third_party/MX/Controller.php";

class CMS_Controller extends CI_Controller {

    public function __construct() {
        parent::__construct();
    }

    public function show_something() {
        echo "something shown";
    }
}

谁知道这里有什么问题？