getting a not found error

Where is your index.php file located to the system and application folders?

I have my index.php under public_html

application
public_html
-- assets
-- index.php
system

With that setup I have to do a '../application' and a '../system' in the index.php file.

I have index.php directly in /var/www/html/sub_crud/. 

sub_crud
--application
--assets
--system
index.php

proof that an old dog can learn new tricks