As noted in our emails last week:
You're going to have to go to the rooftop. Be prepared to use a taller mast so that you can experiment with various heights for the antenna. UHF signals that have to "bend" over terrain will tend to form "layers" of hot and cold zones and you're going to have to experiment with the antenna's height to find a "warm" zone.
Visit http://www.hdtvprimer.com/ANTENNAS/siting.html and see the section right after the cartoon.
Going to the 91XG over the DB4e will in no way assure you of success with that ION stations.