sesion problem

Hi

I have 1 domains with 3 sub domains I want to share login on all 3 sub domain and main domain I am using following code and It should work.

session_set_cookie_params(3600, '/', '.mydomain.com');
session_start();


Any Idea?

I want to know "has it something to do with server configuration?" or its because of something else?

Thanks.

I have one configure.php in every sub domain and the main domain which has above two lines.

Should I use one files between all sub domains or this is ok?