Sessions across sub domains

I am trying to use the same session on all my subdomains but it is not working.

I added the follwoing line to my php.ini session.cookie_domain = .domain.com but this does not solve the problem. any other suggestions of what I shoild do?

Did you stop and start your web server to get any changes made to php.ini to take effect?

Did you confirm that the value was changed using a phpinfo(); statement in a .php file?

Also, only cookies set after the change will work across the subdomains.