找不到另一个控制器的CodeIgniter 404页面

首先，我想为我的英语道歉，=）。我正在制作一个web应用程序，但当将程序流重定向到另一个controllador时，我收到了以下错误："找不到404页"。类和文件都是大写的，就像我在其他帖子中读到的那样，可能不是。提前谢谢。

这是通过"重定向"调用"活动"的主控制器（Auth controller）：

class Auth extends CI_Controller {
public function __construct() {
    parent::__construct();
}
public function index() {
    redirect('auth/login');
}
public function login() {
    if (!$this->input->post())
    {
        $this->load->view('templates/main_template', array(
            'title' => 'Login',
            'header' => $this->load->view('templates/header', null, TRUE),
            'content' => $this->load->view('pages/login', null, TRUE),
            'footer' => $this->load->view('templates/footer', null, TRUE)
        ));
        return;
    }
    $this->form_validation->set_rules('useremail', 'Useremail', 'trim|required|xss_clean'); // trim: quita espacios; required: campo requerido; xss_clean: elimina posibles inyecciones sql; callback_user_auth: otras funciones y llamadas, en este caso llamada a funciónq que autentifica al usuario
    $this->form_validation->set_rules('password', 'Password', 'trim|required|xss_clean|callback_user_auth'); // |callback_user_auth
    if ($this->form_validation->run() == FALSE)
    {
        // LOGIN VIEW (home)
        $this->load->view('templates/main_template', array(
            'title' => 'Login',
            'header' => $this->load->view('templates/header', null, TRUE),
            'content' => $this->load->view('pages/login', null, TRUE),
            'footer' => $this->load->view('templates/footer', null, TRUE)
        ));;
    } else {
        redirect('activity/list_actividades');
    }
} 
public function user_auth($password) { 
    $useremail = $this->input->post('useremail');
    $user = $this->User_model->authenticate($useremail, $password);
    if ($user)
    {
        // valid user, set session data
        $this->session->logged_in = array(
            'useremail' => $user->email,
            'username' => $user->name,
            'group' => $user->group // CAMBIO EN LA BASE DE DATOS 
        ); // GROUP POR ADMIN. DEPENDIENDO DEL GRUPO SE TIENEN UNOS PERMISOS U OTROS

        return TRUE;
    }
    $this->form_validation->set_message('user_auth', 'Invalid username or password');
    return FALSE;
}
public function logout() {
    unset($_SESSION['logged_in']);
    redirect('auth/login');
}

活动控制器：

class Activity extends CI_Controller {
public function __construct() {
    parent::__construct();
    // check for the session here... in theory
}
public function index() {
    redirect('auth/login');
}
public function list_actividades () {
    $this->load->model('Activity_model');
    $data['actividades'] = $this->Activity_model->getAll();
    $data['grupo_usuario'] = $this->session->logged_in['group'];
    $this->load->view('templates/main_template', array(
        'title' => 'Lista de Actividades',
        'header' => $this->load->view('templates/header', null, TRUE),
        'content' => $this->load->view('templates/lista_actividades', $data, TRUE),
        'footer' => $this->load->view('templates/footer', null, TRUE)
    ));
}