AppleScript or Automator script to Change Mail Subject

Question

The following AppleScrip works great with Microsoft Outlook and I tried to change the name to Mail and it did not work
tell application "Microsoft Outlook"
          try
                    set theMessage to item 1 of (get current messages)
                    if class of theMessage ≠ incoming message then error -99
          on error
                    display dialog "please select an incoming message before running
this script" buttons {"Abort"} default button 1 giving up after 10
          end try
          set oldSubject to subject of theMessage
          try
                    set newSubject to text returned of (display dialog "Enter New
Subject:" default answer oldSubject)
          on error
  -- user cancelled
                    return
          end try
          set subject of theMessage to newSubject
end tell
What I am trying to do is create an Automator script that can be added to my usr/Library/Serices folder that will let me change the Subject of an OS X 10.7 Apple Mail message. 
I am s novice on AppleScripts so some help will be appreciated

Answer 1

The error I get when I edit Microsoft Outlook to Mail says
Expected “,” but found plural class name.