I have terrible problems trying to use my sandbox accounts to test Paypal functionalities.
I have about four of them, I made some recently since I assumed older ones might have stopped working or expired.
The problem is: every single one of my sandbox accounts work, I can log in perfectly, but the trouble start when I try to log in from a real "Buy it now" button, then all I get is "Please check your username or password" although I am 100% sure they are correct.
It looks like all my API settings are correct too.
In all honesty, the Paypal help pages are not really user-friendly IMHO.
Does anyone else recognise this problem,or even better, have a solution, as this is driving me up the wall?