After install prefeclty debian server my $_SESSION dont work more

hi, i have some problems, after install ispconfig on debian : https://www.howtoforge.com/perfect-server-debian-wheezy-apache2-bind-dovecot-ispconfig-3 my website use $_SESSION, and stop work, some can help me? thanks for help.

if i put my website in antoher host work prefectly not problem of the code, and before install work fine but after install dont work more.. thanks for help.

 

only say: [Sun Mar 26 10:27:09 2017] [error] [client myip] PHP Notice: A session had already been started - ignoring session_start() in /var/www/shop/mgvipstemp.php on line 3, referer: http://mywebsite/shop/

 

ok forget is my bug, i try now in another browser and work fine sorry for this.