tripspec, sometimes it takes quite awhile for the adsense instance to catch up. It's been awhile since I used adsense, but when I did, it could take up to a half hour before the graphic or box would show. And if your page is cached, then you really have to wait. I would go ahead and try it again, then revisit the page an hour later, also dump the cache in your wiki after you install adsense by control panel/tools/system cache and empty it, or at tiki-admin_system.php
I have never had an adsense show up instantly.