I am informed that the serial number is valid but that it cannot find a version of Flash to upgrade from, despite the fact that CS4 is installed. On the drop down menu of valid products only Flash 5 is available. Any idea what's going on?
Adobe support were not any help. They told me the serial number was not valid despite the error message saying "The serial number you entered IS valid, but a qualifying product cannot be found on this computer". Additionally the support phone number doesn't exist from a British landline. Very helpful indeed.