With Yahoo's recent update, they changed the url that Snapshop and mini-cart used to submit and pull information from the iframe (the link between cart and front side). Existing code will add items to cart, however the checkout button will not work when you are back on the front side of the store. Clients are in need of a JavaScript upgrade to Mini-Cart files to patch the update. Solid Cactus will not support any 3rd party code, this update will only update Solid Cactus Mini-Cart and Snapshop.