Why controller under admin subdirectory not found?

In codeigniter  4.3.7  I created new controller file
under subdirectory app/Controllers/admin/Category.php with defined :

PHP Code:

    <?php

    namespace App\Controllers\admin; // Not sure - is it correct ?

    class Category extends BaseController
    {
        public function index()
        {
            echo '<pre>::Category::'.print_r(-1,true).'</pre>';
            return view('admin/categories/index', []);
        } 


But urls

Code:

http://localhost/CIProducts/admin/categories/index

not opens  my controller, as I expected and returns 404 error

while url

Code:

    http://localhost/CIProducts

returns default homepage

I added in file Routes.php line with "admin/" url:

PHP Code:

    <?php

    use CodeIgniter\Router\RouteCollection;

    /**
    * @var RouteCollection $routes
    */
    $routes->get('/', 'Home::index'); // This link works ok

    $routes->get('products-by-category', 'ProductsByCategory::index');  // This link works ok

    $routes->get('admin/category/index', 'Category::index');  // This link DOES NOT works with 404 error

    // $routes->get('admin/category/index', 'admin\Category::index'); // uncommented THAT RETURNS 404 


How to reference controller in file app/Controllers/admin/Category.php with "admin/" in url?


Thanks in advance!