Help set up Push Notification certificates for Newsstand Mag+ app

We have gone with Mag+ as our publishers for a Newsstand magazine and app but decided to build our app ourselves. In the IOS Provisioning Portal we have created a Production and Development Push SSL Certificate but when I download them and export to a .p12 and upload it to the Mag+ Publish account we get this error 'Apple Push Notification Certificate does not seem to be a apn certificate file, make sure you have uploaded the right one., must be issued for the app with bundle id: [login to view URL]' Please only bid if you are sure you can do this and speak good english, thanks.