I creates a new Buy it Now button using my merchant account, and am trying to test it. The link works fine from my application but when it opens the Login page to PayPal, I enter my Sandbox account info using the correct Username and Password, but I get this error;
I know I am using the correct info, I even tried my other Sandbox account but get the same results. What's up? Why is it so difficult to use PayPal buttons?