$_SESSION['cart']->total += addedAmount not showing up in $cartShowTotal

[tcarden]

Hey Everyone,
it's Mr. HazMat here again...

i'm trying to add a HazMat fee (using a Session variable) to the cart total
like so....

$_SESSION['cart']->total += $_SESSION['hazMatFee']; 

i've echoed out the 2 variables:

$_SESSION['cart']->total and $_SESSION['hazMatFee'];

on the tpl_shopping_cart_default.php and they seem correct.

but the $cartShowTotal is not reflecting the added fee.
and subsequent checkout pages are not showing it either.

can someone advise on how to get this to be added to the total?

btw - in the class constuctor method i'm using
'NOTIFIER_CART_SHOW_TOTAL_END'