If you have entered your Mals account information correctly under Catalog setup in the storeadmin area of your website and your buy now button are giving the error ERROR: Link verification Failed when clicked to add and item to the cart follow these steps.
1. login to your Mals account and click on the Cart Setup tab
2. click the arrow next to Advanced settings in the left menu
3. click Link Verification from the drop down
4.Uncheck the Test all my links against hash verification function option
5. click submit
Go back to your website and try your buy now button again. The problem should then be corrected.