I use session variables to store user details in PHP. I do development under windows7 using WAMP setup and every thing works as programed. When I copy the files to Ubuntu 14.04 server session is not working. After some web search I found that default session.save_path is under /var/lib/php5. But I was not seeing any session files created there. So I set the session.save_path to /tmp in /etc/php5/apache2/php.ini and created a test.php with just start_session(). This created a session file in /tmp. However when I try to do same in my project I see the error log reporting that variable _SESSION is not defined and also I do not see any session files being created in /tmp.
How do I find what is the problem.