reinstalling acrobat X

I have an cd which I used to upgrade to Acrobat X in the past.  Recently I had to format my hard drive.  When I try to re-install Acrobat X using the product code that is on my Adobe account, I get a message that "there is no older version to upgrade from" so I can't install it.  Since I was able to register this before, Adobe has a record of my using Acrobat X on my computer.

How can I install Acrobat X?