Have you rebuilt your database (www.yoursite.com/dev/build) to add the new fields for the image?. Next thing you can check is if you go into your database (with phpmyadmin or similar) and you select the 'Page' table you should see a BannerID column. Check this value - if your upload worked then this should not be 0.
Todd, what exactly was in the template file that was messing up your link? I'm having the same problem, but only have one main template (Page.ss) and as far as I can tell not even removing my includes fixes the issue. Thanks