The Do Not Track feature is available in Internet Explorer, Mozilla Firefox and Google Chrome when AVG 2012 is installed. Please make sure that you have the latest version of AVG installed. You can get complete instructions on how to install the latest version in the article Upgrading to AVG Free 2012 from older version of AVG Free.
If AVG 2012 is installed and the Do Not Track button is not available in Internet Explorer (note that other browsers are not affected):
If the Do Not Track button is not available after clicking the >> button or to make it permanently available: