Arithmetic code not working

[FlashDance]

I've written this code and echoed everything and everything is coming out right, but the math isn't happening. Can anyone see why?

PHP Code:

$totalbeforequantity = $_SESSION['cart']['content'][$_POST['id']]['sizes'] + $_SESSION['cart']['content'][$_POST['id']]['sizem'] + $_SESSION['cart']['content'][$_POST['id']]['sizel'] + $_SESSION['cart']['content'][$_POST['id']]['sizexl'];
    $beforeprice = $totalbeforequantity * $row['price'];
    $_SESSION['cart']['total'] -= $beforeprice;
    $_SESSION['cart']['content'][$_POST['id']]['sizes'] = $_POST['quantitys'];
    $_SESSION['cart']['content'][$_POST['id']]['sizem'] = $_POST['quantitym'];
    $_SESSION['cart']['content'][$_POST['id']]['sizel'] = $_POST['quantityl'];
    $_SESSION['cart']['content'][$_POST['id']]['sizexl'] = $_POST['quantityxl'];
    $totalafterquantity = $_SESSION['cart']['content'][$_POST['id']]['sizes'] + $_SESSION['cart']['content'][$_POST['id']]['sizem'] + $_SESSION['cart']['content'][$_POST['id']]['sizel'] + $_SESSION['cart']['content'][$_POST['id']]['sizexl'];
    $afterprice = $totalafterquantity * $row['price'];
    $_SESSION['cart']['total'] += $afterprice; 


[Adee]

Can you give some example output?

[FlashDance]

Never mind, it worked.. had some weird cookie issue.