Url harus pake index pada codeiniter

kok pas saya tulis url seperti ini page not found yah ? http://localhost/terbebas-ci/user/3456

tapi pas saya tambahin index setelah user kaya gini jadi http://localhost/terbebas-ci/user/index/3456

ini kode saya di class User.. mohon diperbaiki, hehe

<?php

class User extends CI_Controller {

	public function __construct()
	{
		parent::__construct();
		$this->load->model('User_model');
	}

	public function index($kode)
	{
		$data['judul'] = 'Detail Data User';
		$data['user'] = $this->User_model->getUserByKode($kode);
		$this->load->view('templates/header', $data);
		$this->load->view('users/index', $data);
		$this->load->view('templates/footer');
	}
}