I'm trying to implement in my CI project this code: http://www.sanwebe.com/2012/07/paypal-expresscheckout-with-php/comment-page-2#comments
But i get this error, when i try to login with my sandbox account. "We are unable to validate your information. Please try again."
I configured the config.php with the right credential and i try to login with another sandbox account.
Why i get this error?
