OK, just tried this plugin.
I did all the setting (show 5 ads and 1 column) and went to add an ad. In the Slots dropdown box, I get nothing. I saved it and all I get is the default image on my site.
I added another ad but still, nothing showing in the slot. Saved and went to my site. Still the same.
I went to Manage and I see the two ads I saved but in the Slots column, they are all showing zero. WTF?!?
Oh, btw, how would I go about centering the ad images when it's in one column mode and also, I need a space between the Ads widget title and the start of the first ad image.
I'm on wp2.6.1.