I'm using ZipShip and everything works correctly for shoppers who are logged in and using the Members' Cart.

But for anyone using the Visitors' Cart, the Shipping Estimator gives the following errors (and updating with a postal code makes no difference):

Warning: Attempt to assign property of non-object in /home/capeinfo/public_html/wineshop/includes/modules/shipping_estimator.php on line 109

Warning: Attempt to assign property of non-object in /home/capeinfo/public_html/wineshop/includes/modules/shipping_estimator.php on line 124
I've tried everything, to no avail. Can someone help please?