I am trying to test out IAP for a Windows App using the Windows 8 object, but every time I prompt the user to make a purchase and choose an OK result, the purchase fails. The "Test Mode" option for the Win 8 object is set to yet, and I am testing in Visual Studio as a Windows 8 app. I simply have a button for the user to buy something, but the "On Successful Purchase" event is never triggered. Anything I am missing?