customise site admin

Hi,

I have tried the following instructions http://dev.day.com/docs/en/cq/current/developing/customize_siteadmin.html and find that it does not seem to work. I even downloaded the shared package example and still it fails to display the extra column. The josn page seems to work just the displaying of the column does not seem to work. I have tried this on a new instance of 5.6.1 any help will be greatly appreciated.