Where did you buy that upgrade CD?
Call Adobe Customer Service (not tech support) to find out why you get that error message. Use the Contact link at the top of this page.
I take it this is a recent purchase, and it was cheap. Be aware that with old technology, you will be limited in both the apps that will still run on it and with the degree of support you'll be able to get from any source.
But as Ramón suggests, you may have been given a bum deal on the software...
Neil