Bug in extended helpers?

[eluser]olof84[/eluser]
Thanks for taking time to check the problem. I don't know why I don´t get any error. Here is my code:

MY_string_helper.php

Code:

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

if ( ! function_exists('this_bug_test'))
{
    function this_bug_test()
    {
        echo 'Inside this bug test.';
    }
}

My controller:

Code:

public function index($adv_slug)
    {
        
        echo this_bug_test();
}

When I run it this shows up: 'Inside this bug test.'.

Here are my autoload files:

Code:

$autoload['packages'] = array();
$autoload['libraries'] = array('database', 'session');
$autoload['helper'] = array('url', 'sh_basic_helper');
$autoload['config'] = array();
$autoload['language'] = array();
$autoload['model'] = array('model_user');

EDIT:
I see now that only some of my extended helpers are available (without me adding them to autoload). The MY_string_helper and MY_url_helper are available, but not MY_text_helper/MY_array_helper. The first two helpers have I used before in my project, but removed from the autoload file. The last two have I never used before.