Coupons not working

When we add the coupon code in the checkout we go to a blank screen with the following errors:

Warning: Invalid argument supplied for foreach() in /home/xxx/public_html/templates/gk_bikestore/html/com_virtuemart/cart/default_pricelist.php on line 36

Fatal error: Call to a member function createPriceDiv() on a non-object in /home/xxxx/public_html/templates/gk_bikestore/html/com_virtuemart/cart/default_pricelist.php on line 157

Can anyone advice why our coupons are not being accepted in our cart?

Thanks,

Hello,

This is solved, seemed to be a problem in the way gift certificates was calculated.