Adsharing not working properly for singlesite install


i have installed ad sharing on a single site install and it doesnt seem to be working properly. i can select before and/or after posts, and the stock ads display fine without a problem.

however, when an author puts his ad code in there, the bottom ad spot below the content will never rotate to his ads and the top spot doesn't show either his code or the stock code, it just disappears. i can get their ads to display if i put nothing in the stock spots, but that's no fun at all.

any idea on what might be happening here?