Pay Per View - Security Header - Not Valid "10002"

Each time we attempt to utilize the pay per view option we get the following message,

"There was a problem connecting to PayPal to setup your purchase. Please try again. •10002 – Security error – Security header is not valid"

The post we're testing this on is - http://www.theempowermag.com/leed-and-the-contractor/

Please help!