I've got a banner ad(125x125) to fall back on "Your Ad Here" that is not displaying at all. There is just empty space where it goes. I have set it up a few days ago, but still nothing, I checked for js errors and nothing shows up, I can see the code is working as it loads the 1x1px image and I see the stats are displaying for pageviews, but no "Your Ad Here" message/link. Any ideas?
Actually, I think I figured out what may have been going on. If the last field you edited was the "fallback" when setting up the banner, the JavaScript code wasn't updating (and therefore not including the fallback parameter). If you grab the JavaScript again, it should have the proper fallback parameter in it now (if you saved your ad, it should already reflect if you just go and edit it... no need to recreate it).