Today we’ve received an interesting question:
“I have an issue on my site the advert at the top of the post displays nearly all of the time. The advert the bottom of the post displays occasionally. Sometimes the advert at the bottom of the page displays a grey box, sometimes it doesn’t display at all”
The answer is very simple and does not need much words:
That is because any ads above the fold (the top ones) are more popular by advertisers. So advertisers are explicitly looking for ads which are above the fold. As a result ads below the fold (ads which are not visible without any scrolling) are booked less. Every time you see a blank ad box means that there is no one advertising for this ad spot.
You can try to show more ads on top of the site or create bigger ones at the bottom of the site. This might increase the ad impressions than.
We hope that helps to understand why AdSense is occasionally not shown.