well, let me explain few things one by one:
1) I've found on one thread that the extension object work only on Ajax Client, so IE client goes out of picture.
2) I've set IE plug-in to be the default client in my server settings as i want my On Open triggers to work in few other documents used by IE users.
3) Since, extension objects work only on Ajax client, i'm using Mozilla to view this particular qvw having the Org Chart. even after manually selecting Ajax client form the Favorites & Profiles section of the Access Point, the chart is not visible. even after disabling the IE client and using the Full browser version for this particular document in the server the chart is not visible.