Comment on How to Add AdSense to WordPress by SEO Dave.
When you look at the AdSense code there should be no spaces between the speech marks.
Correct AdSense publisher ID added
Wrong AdSense publisher ID added
"pub-8325072546567078 " or " pub-8325072546567078"
If it looks like the last two examples your ads will be blank.
Easy mistake to make, have it all the time with my Stallion WordPress SEO AD Theme users that has AdSense, Chitika, Clickabnk, Kontera, Infolinks and Linkwords ad networks built in. For monetizing a site with AdSense for example all they have to do is add their pub-######### number and quite a few add spaces before/after :-)