building an efficient admin control panel

[eluser]JOKERz[/eluser]
in admin.php

Code:

class Admin extends Admin_Controller {
    function Admin() {
        parent::Admin_Controller();
    }
    function index(){
        echo "this is admin.php";
    }
    function logout() {
        $this->session->destroy();
        redirect('', 'refresh');
    }
}

how to use logout function?
when i go to "admin/logout" it return 404 Not Found

so i try to create admin_logout.php and add this code

Code:

class Admin_logout extends Admin_Controller{

    function Admin_logout(){
        parent::Admin_Controller();
    }
    function index(){
        $this->logout();
    }
}

But still return error....