Language setting not appearing in th Acrobat reader

Hi, I am using Acrobat Professional V8 for creating accessible PDFs. I noticed that the language setting is not being displayed when im opening the PDF file using Acrobat Reader V9.
In Acrobat Professional, the language setting was done is below:
File --> Properties --> Advanced, Language field set to "English US."
 
However, when I opened the document in Acrobat Reader and checked the properties (for accessability), the Language field appears blank.
 
Can someone explain and provide a solution to fix this?
Thanks in advance..