defines.php

Hello, I've a problem with joomla 2.5.9.

I put in my ftp joomla on my server but when I want to install joomla it puts me this following error.

Fatal error: require_once(): Failed opening required '/dns/in/olympe/clanfws/Joomla/includes/defines.php' (include_path='.') in /dns/in/olympe/clanfws/Joomla/index.php on line 18