Blank Skyscaper

I just added adsense to a site. I have 4 ad units on the page and all are showing except the skyscraper which is showing blank, anyone know why?

 

If they are all image and text ads, you are only allowed 3 per page. I believe you can only have 2 text link type ads on a page, also. So, max of 5 ads, 3 image and text, 2 text link.

 

You must wait for a while to update adsense ad

 

Yeah they are all text and image.

Its been about 24 hours now, how long does it usually take?

Thanks

 

You can only have a max of (3) AdSense For Content Ad Unit ads per page.

EDIT: Anything above that magical number (3) will NOT show--might even get you banned if AdSense thinks you're trying to spam the ads.

 

It takes about 10 mins to displays, if it is new.
You can add as many units as you want, but not all will show up but blank ads.
You can have max = 3 content units max, 2 referrals, ...

 

Got it thanks guys, Its been a while since I got back into adsense! lol

Can we add other offers, ad networks (CPM) with adsense? or is it against their policy?