I have about 15 sites selected and half of them at least allow image ads. The cpm I have selected is quite generous but still nothing.
Is it perhaps because the selected sites might not carry leaderboard-sized banners or is there another reason why image ads might not show at all?
...bit of an AdWords newbie..
Have you uploaded an Image Ad for each of the 5 sizes? Publishers do select which size ad they will display, and if your ad doesn't fit it won't matter if you have bid a high CPM.
I have found that it is critical to carefully research each of the sites you choose. The page view estimate provided by Google isn't all that fresh-- and sometimes the sites on the list don't display Image Ads at all. Its worth the time during setup, and worth checking back with to see where the ads are being placed... if they aren't prominently featured, you may want to consider a new site.
It takes some time, but when you find a good one, it can really work out well.
... is there another reason why image ads might not show at all?
Esllou, in addition to the ideas suggested by arinick, this could be a simple approval issue.
Essentially, image ads will only show after they've been reviewed and approved - and the time-to-review can vary with volume of incoming ads.
I hope you're getting impressions now, but if you are not, the best way to find out why is to contact AdWords support and ask them to take a look. Be sure to mention the campaign(s) and Ad Group(s) you're concerned about.
AWA
