title: Routes error on middleware
body: <p>Hello im getting a error of "Argument 2 passed to Illuminate\Routing\Router::group() must be an instance of Closure", i believe i did everythign well, but still getting this error, what im doing wrong?
  My laravel version is 5.2</p>
  
  <p>Code Routes:</p>
  
  <pre><code>Route::group(['middleware' =&gt; ['auth', 'admin'], function() {
          Route::get('admin/dashboard', 'PageController@dashboard');
  
  other routes...
  }]);
  </code></pre>