I'm testing the Classifieds plugin with the PayPal Sandbox. I've selected the Sandbox option and used the Sandbox API usernames, password and signature.
When I make a test subscription, I use a Sandbox buyer account. I get this error when I login at sandbox.paypal.com:
The link you have used to enter the PayPal system is invalid. Please review the link and try again.
Am I doing something wrong?