variable $_SESSION['payment'] suddenly disappeared from checkout_success page

I just created a function which used the $_SESSION['payment'] variable to display some texxt if it a certain payment.
But suddenly it didn't work :/
I checked the content of the $_SESSION['payment'] variable, but it was null.

Can someone help why that happend ?, or tell another way I can get what kind of payment my customer using?

I'm running zen cart 1.5.1

/LasH

$_SESSION['payment'] is indeed null at the checkout_success page, because payment is already completed and done.

Better to use $order_summary['payment_module_code'] instead, as per: http://www.zen-cart.com/content.php?322-Integrating-Sales-Analytics-and-Affiliates-Tools

Okay, maybe some chache was used when I programmed it.

but I dont have that variable. I have just printed the variable out using var_dump and got this:
["order_number"]=> int(90)
["order_subtotal"]=> float(50000)
["credits_applied"]=> int(0)
["order_total"]=> float(50000)
["commissionable_order"]=> float(50000)
["commissionable_order_formatted"]=> string(18) "50.000,00 EUR"
["coupon_code"]=> NULL