9.0.0 for Acrobat 9), this means that you need to first upgrade your installation to the latest available version. When you install a new version of Acrobat, you always end up with a x.0.0 version (e.g.
This does not mean that Acrobat 9 does not work anymore, it means that you will not get any security updates for new security threats. You may remember that Adobe “end of life’ed” Adobe Acrobat 9 more than a year ago. Update: There is now a Knowledge Base article about updating older versions of Acrobat/Reader: