Quote Originally Posted by vmolasi View Post
We are sorry for the inconvenience. The PayPal account authentication settings are not yet set up, or the API security information is incorrect. We are unable to complete your transaction. Please notify the store owner so they can correct this problem. (10002) 10002 Security error - Security header is not valid
This means, as it says, that you've entered invalid information for the API username/password/signature fields in your module settings, and/or you've selected "sandbox" when it should be "live" or vice-versa.