Hello. I try the sandbox before launch the form in the "real life". But when i am going to (sandbox) pay, Paypal give me this message:
The link you have used to enter the PayPal system is invalid. Please review the link and try again.
and a botton: return to merchant. If you click at this botton, you will go to "Canceled Page".
I am trying a annual subscription. I read at google that its a sandbox issue, but in real transactions all is ok. Do you have any notice about this?