Problem with translation block when switching to greek language

Hello
I am trying to use i18n with a 3 lingual site (english, german and greek).
I am using the translation block to switch language.
Everything works but when I try to switch to the greek language (el), nothing
happens. The interface remains the same (e.g. english or german as it was previously)
and the navigation links are not updated (e.g. they remain en/blog, en/user, etc as they were previously).
I don't have any problem with german or english.
Drupal: 5.5
i18n version: 5.x-2.2
PHP: 5.0.5
MySQL:4.1.22
Web server: Apache/1.3.37 (Unix)
You can take a look at http://demo.aladdinweb.net/
Thanks in advance