I have a newer computer and I am trying to install Acrobat 9 pro. when I try to open the program it will not let me complete set up because software does not have acrobat 9 in the drop down list.

It sounds like you might be dealing with an upgrade situation where it is asking you to select the previous 'qualifying' version that you upgraded from.  If that's the case then you will need to find the serial number for that older version as well.