ReflectionException in Container.php

How to i can fix ReflectionException in Container.php, Class DashboardSidebarMenu does not exist error. I created: route.php:

Route::group(['middleware' => 'DashboardSidebarMenu'], function () {
        Route::get('/','PostsController@index');
        Route::get('ajax/{lastArticleTime}', 'PostsController@ajaxIndex');
        Route::get('/post/{id}',[
            'as'  => 'post.show',
            'uses' => 'PostsController@show'
        ]);
    });

Middleware/DashboardSidebarMenu.php:
namespace App\Http\Middleware;
use Closure;
use Menu;
use Auth;
class DashboardSidebarMenu
{
/**
* Handle an incoming request.
*
* @param  \Illuminate\Http\Request  $request
* @param  \Closure  $next
* @return mixed
*/
public function handle($request, Closure $next)
{
Menu::make('DashboardSidebarMenu', function($menu){
        $menu->add('MAIN NAVIGATION', array('route'  => 'post.index','class' => 'header'));

        // post
        $posts = $menu->add('Posts', array( 'class' => 'treeview'));

        $menu->posts ->append('</span> <i class="fa fa-angle-left pull-right"></i>')
                    ->prepend(' <i class="fa fa-edit"></i> <span>');

        $menu->posts ->add('All Posts', array('route'  => 'dashboardArticles'));
        $menu->posts ->add('Add New', array('route'  => 'article.create'));
        $menu->posts ->add('All Categories', array('route'  => 'cats.index'));
        $menu->posts ->add('Add Category', array('route'  => 'cat.create'));

        // quiz
        $quizs = $menu->add('Quizs', array( 'class' => 'treeview'));

        $menu->quizs ->append('</span> <i class="fa fa-angle-left pull-right"></i>')
                    ->prepend(' <i class="fa fa-edit"></i> <span>');

        $menu->quizs ->add('Add Quizs', array('route'  => 'quizzes.create'));
        $menu->quizs ->add('All Group Quiz', array('route'  => 'group_quizzes.index'));
        $menu->quizs ->add('Add Group Quiz', array('route'  => 'group_quizzes.create'));

        // users
        $users = $menu->add('Users', array( 'class' => 'treeview'));

        $menu->users ->append('</span> <i class="fa fa-angle-left pull-right"></i>')
                    ->prepend(' <i class="fa fa-edit"></i> <span>');

        $menu->users->add('All Users', array('route'  => 'users.index'));

        if (Auth::user()->level < 3) {
            $menu->users->add('Add user',    array('route'  => array('user.create', 'id' => Auth::user()->id)));
        }            

        $menu->users->add('Your Profile',    array('route'  => array('user.profile', 'id' => Auth::user()->id)));

    });
    return $next($request);
}

}