Can't get Mac discount upgrade to work - won't accept serial no.

  • Hi, I purchased Aerofly RC 5 for Mac from Ikarus USA in December 2010. Just now I upgraded to Aerofly RC7 through the App Store. Then I have tried to do an in-App purchase to accept the offer to upgrade to RC7 Ultimate for a discount price, but when I enter my serial number and try to proceed, it keeps telling me that there's an error with entry of the serial number. However this is a genuine copy, and the serial number is on the CDs that I purchased. When I go to the support page and enter a question, it won't work, saying there's an invalid response. Possibly it's also rejecting my serial number. Can anyone help?

    Thanks,
    Andrew

    Dynamic Soaring Addict.