ERROR - User is not allowed to perform this action

Getting this error when trying to complete a sale:

There was a problem connecting with the paypal gateway. (CODE)550001 User is not allowed to perform this action

API was set up and approved.

URL: http://petemarovichimages.com/2012/11/18/a-culture-on-the-brink/

select a donation and click "Back this project"

error message on next page