Step 1:  Please make sure user us using Internet Explorer, not any other browser.

Step 2: If user is using Internet Explorer and continue to get this error 

  a. Open Internet settings dialog and go to "Programs" tab and then click "Manage add-ons"

b. Select Show "All add-ons" and then make "Microsoft Silverlight" is enabled as shown below, if not go ahead and enable it. restart your browser and try to use Notify Again