not able to retrieve old session variable values in php
<p>Hi i am new to PHP.I am having "item.php" page and "cart.php" page. In item.php 3 checkboxes are available. if i click on one checkbox from item.php the value is sent to to cart.php page. however if i go back and select another checkbox the old value is not retained. Only the new value is getting printed. 
I am storing the retrieved checkbox value in a session variable in cart.php  but still not able to retrieve the old values selected. Can anybody help me out? Thanks in advance</p>
