Can not add products to cart

Hi, I am having an issue with getting the order moved over to Alibaba Express when someone orders from my website. The order is listed under the AliExpress orders in the site however when I click on the Order With Extension it goes to the AliExpress portal to place an order I get, Sorry, the page you requested cannot be found. I verified that the product is available and can order on the website manually. In the corner of the page a red banner show, Can not add products to cart/

Thank you,
AArt