CPM advertising. You're being site targeted; the advertiser has picked out a number of sites (or all sites) and is paying per thousand views rather than per click.

Thanks for the explanation nutmeg, I had no idea. Does this mean that after 1,000 views I will experience the opposite, that is, I will receive a payment without clicks, instead of a click without payment?

Ok, I guess I misread your initial post. You could have several things going on - it could be clicks worth less than one cent (it's possible to advertise for .01/click, so figuring Google takes some percentage, it must be possible to earn less than a cent a click) or it could be that you are being site targeted AND you have clicks that Google determined aren't real, so they didn't pay you for them.

Unless it's happening on a grand scale, over hundreds and thousands of clicks and pageviews, I wouldn't worry too much over such small amounts.

(netmeg)

Thanks again Nutmeg. My earnings are minor compared to a lot of people here so it is no big deal. I wasn't unduly worried but just a bit curious as to why. It's always good to see clicks coming in, but not so good when they don't generate any earnings.

The bottom line is that I will never know why exactly, but at least now I have a few more ideas.