I have a theme from themeforest installed which is built to work with WP Ecommerce. Everything works fine, however when I select "Shipping: ON" in the backend, the items no longer update the cart (does it with ajax). When shipping is off, it works fine. The JS console says: Failed to load resource: the server responded with a status of 500 (Internal Server Error): website.com/products-page/category/index.php?ajax=true Anyone any clue to this? It says on the website jquery could be loading twice, but I dont think thats the problem if shipping turned off works fine...