I am trying to integrate PayPal subscription using PayPal payment standards button. Initially I am getting a Subscribe button and when I clicked on this button it is redirecting to a new page where it shows two buttons. One is Subscribe using debit or credit card and another is Log in to subscribe. When I click on Subscribe button under Subscribe using debit or credit card it's always redirecting to a page showing a message "We're sorry Things don't appear to be working at the moment". But if I click on check out button under Log in to subscribe then I am able to process the subscription. Currently I am testing this using sandbox account. But when I use live account, both the buttons are working. Please guide me through this.