For some reason, the Adsense ads that I manually paste into my Wordpress posts don't display. Well, they only display some of the time

Does anybody know why? The ads on my sidebar always displays though ...

Thanks in advance!

Usually it's because you don't have enough text on a page for Adsense to figure out what the page is about.

What's the site?

It can be either bcoz there's less content on your page or the niche you target has less ad offers, Give us your site so we can take a look and see what's really wrong