[Problem with session]

Although I donot choose the Item. The item will be shown in my cart with amount=0. How can I change my code so that only selected item will be shown in my cart.

if(isset($_SESSION[$line[0]])) {
                $menge = $_SESSION[$line[0]];
                 } else {
                
                 $menge = 0;

                 }  

 

Thanks