Session on login problem. PHP

[HotelNine]

I have recently released my old school cms of phoenixphp. But ive now added login, register and im doing profile pages atm. I seem to be having 1 problem. When i login... It doesnt register like um, it doesnt start my session. Could someone assist me? Thanks.

 

[Livar]

if isset($_POST['login']) { 
session_start();
}