Google Adsense...

So, I'm sure that I'm probably breaking some Adsense rule by mentioning them on my site, but today -- I just don't care. I'm a little upset.
I've have Google Adsense on my webpage for a few months. It's not like I'm making big bucks. I think right now I've earned a grand total of $2.74. I'm not even upset about that, as you have to have so much traffic click one of their links to make even start making money. What I'm upset about is the fact that for three days or more, I haven't had a real ad. Just the public service ones, which kind of upsets me. I run more than one blog and the other blogs didn't lose their ads, so why would my main blog?
It's a mystery to me.