route dose not work to sub folders

I have Front folder in the controller
and inside it i have Home.php file
in the file have index function

when i make this in the config/route

PHP Code:

$route['default_controller'] = 'Front/Home/index'; 


it dose not works
and route to files in the sub folders of the controller dose not works , i must put the class in the controller directly to be accessed by routes .

I use codeigniter 3.0 and  This problem was not happened in codeigniter 2.2.0