I had Acrobat XI Pro installed on my old computer.
I downloaded a trial version on my new computer and ended my product key.
The software downloaded and installed but when I go to use it I get this message "Serial number you provided is valid, but a qualifiying product could not be found on this computer".
Apparently this is due to my product key being an upgrade licence (I had a previous version of Acrobat before I upgraded on my old machine.
How do I get XI to work on my new machine?
During the install you SHOULD be provided a screen where you may enter your old product serial number