I am using prestashop and love it but i have been having a problem with the payment gateway for paypal. I have posted on their forum and sent an email to support but heard nothing back, this is the error i am getting i have put sandbox to inactive and the api information is correct Please refer to logs: PayPal response: TIMESTAMP -> 2011-09-08T11:10:50Z L_ERRORCODE0 -> 10002 L_SHORTMESSAGE0 -> Security error L_LONGMESSAGE0 -> Security header is not valid L_SEVERITYCODE0 -> Error PayPal returned error