Session class only work on localhost...

[eluser]Daniel_C[/eluser]

its strange, because i still can retrieve the minimum data (ip,user agent, session id, time stamp), although there is no cookie created!

Sounds impossible to me, go to your application and execute the following code in the URL:
[removed][removed]([removed]);

If the browser shows content like ci_session=BASE64 so the cookie is correctly created.

And review too the session expiration time.