problem with uploading CI on the web server

Hi. I have some problems with upload my CI project on the web server. Until now I hosted it only locally on my xampp but i wanted to upload this on the web.
But it's not working.
I thought it was some config.php issue, but after that I've uploaded vanilla CI 3 to test if it's works. So the welcome controller works fine. but when i've created some test controller like:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class hello extends CI_Controller {

public function index()
{
echo 'aaaa';
}
}

After that i've entered http://mydomain.com/index.php/hello .
So it should print 'aaaa', right? But it didn't. It's just shows 404 error page. And I have this issue with every controller.

Am I doing something wrong? Did I missed something? Any ideas or anything?
Thank you for your help.