Is there a good reason why you are not using a valid filepath to the ico file as per the posts where it appears you sourced your code?
see
http://stackoverflow.com/questions/2...-while-loading
When I tested that code, it changed the icon in the app header and the icon associated with the app when Alt-tabbing through the available apps but didn't appear to change the icon in the already loaded taskbar. Perhaps that code needs to be run as the application is booting.