Installing ILIAS 4.2.4

I have decided to test different open source LMS (learning management systems).
The first i tried is ILIAS .

I downloaded the file 'ilias-4.2.4.tar.gz' , uncompressed it and uploaded to my web server (folowing installation instructions).

When i opened with the browser http://myhost.com/setup/setup.php i get following errors:

Warning: file(/lang/setup_lang_sel_multi.lang) [function.file]: failed to open stream: No such file or directory in ...ilias/setup/classes/class.ilLanguage.php on line 107

Warning: file(/lang/setup_en.lang) [function.file]: failed to open stream: No such file or directory in ...ilias/setup/classes/class.ilLanguage.php on line 123

Warning: parse_ini_file(/setup/ilias.master.ini.php) [function.parse-ini-file]: failed to open stream: No such file or directory in ...ilias/setup/classes/class.ilSetup.php on line 149

Warning: parse_ini_file(/setup/client.master.ini.php) [function.parse-ini-file]: failed to open stream: No such file or directory in ...ilias/setup/classes/class.ilClient.php on line 56

Warning: dir(/lang) [function.dir]: failed to open dir: No such file or directory in ...ilias/setup/classes/class.ilLanguage.php on line 191

Warning: chdir() [function.chdir]: No such file or directory (errno 2) in ...ilias/setup/classes/class.ilLanguage.php on line 193

Fatal error: Call to a member function read() on a non-object in /home/skills...ilias/setup/classes/class.ilLanguage.php on line 196

After a quick look with google about the problem i didn't find a solution. I have decided to solve the problem myself.

And it was easy. I have changed the file setup/setup.php
After :

if (is_dir("./pear"))
{
    ini_set("include_path", "./pear:".ini_get("include_path"));
}

I have inserted new line:

if(!defined("ILIAS_ABSOLUTE_PATH")) define ('ILIAS_ABSOLUTE_PATH',dirname(__FILE__).'/../');

And now installation works fine!