Code module not setting up

Hello,

I'm trying to set up a code module following the steps in the user guide.

1) I added the module to the psr4 section of the Autoload.php:

PHP Code:

public $psr4 = [
    APP_NAMESPACE      => APPPATH, // For custom app namespace
    'Config'           => APPPATH . 'Config',
    'Modules\YtVideos' => ROOTPATH . 'modules/YtVideos'
]; 


2) Then I tried to add a route to the module's Routes.php:

PHP Code:

namespace Config;

$routes = Services::routes();

$routes->get('admin/videos', 'Modules\YtVideos\Controllers\Admin_YtVideos::index'); 


This has no effect though, although the module's Routes.php gets loaded (error messages get thrown when something's wrong in it).

When I put the above route definition in the default Routes.php, I get the following error message:

Controller or its method is not found: \App\Controllers\Modules\YtVideos\Controllers\Admin_YtVideos::index

As you see, it looks for a Modules namespace inside the \App\Controllers namespace, although the Modules\YtVideos namespace is supposed to be handled as a root namespace.

What am I doing wrong?