Error 404 when trying to reach a link

Try site_url() instead of base_url().
Don't use a firstcaps in url's. Despite the fact that controllers are in firstcaps, the request shouldn't be. So site_url('auth') should work. It will try to open the index function in the auth controller.

thank you.
I am going to try that this morning

unfortunatly site_url is not working either. Should i use route.php to make the things easier ?