Protected routes error in laravel

I have this protected route to be accessed only when the user is authenticated:

Route::get('/checkout', [
    'middleware' => 'auth',
    'uses' => 'Front@checkout'
]);

and the other routes are:

// Authentication routes...
Route::get('auth/login', 'Front@login');
Route::post('auth/login', 'Front@authenticate');
Route::get('auth/logout', 'Front@logout');

// Registration routes...
Route::post('/register', 'Front@register');

And my controller is:

<?php

namespace App\Http\Controllers;


use Request;
use Redirect;
use App\User;
use Illuminate\Support\Facades\Auth;
use App\Http\Controllers\Controller;

class Front extends Controller {

public function register() {
    if (Request::isMethod('post')) {
        User::create([
                    'name' => Request::get('name'),
                    'email' => Request::get('email'),
                    'password' => bcrypt(Request::get('password')),
        ]);
    } 

    return Redirect::away('auth/login');
}

public function authenticate() {
    if (Auth::attempt(['email' => Request::get('email'), 'password' => Request::get('password')])) {
        return redirect()->intended('/checkout');
    } else {
        return view('auth/loginerror', array('title' => 'Welcome', 'description' => '', 'page' => 'home'));
    }
}
public function login() {
        return view('auth/login', array('page' => 'home'));
    }

public function checkout() {
        return view('contactme', array('page' => 'home'));
    }
public function logout() {
    Auth::logout();

    return Redirect::away('auth/login');
}
}

there is a error with the route:

NotFoundHttpException in RouteCollection.php line 161:

via Chebli Mohamed