Problem with 336 x 280 rectangle ad

I have a problem with 336 x 280 rectangle ad.
When I place the ad at my site there are always 4 links
But I want to show only 3 links as here:
http://www.redferret.net/?p=13413
http://www.lifeatmost.com/digital-camera/amadana-sal-compact-camcorder/
http://todaygadgets.com/2009/03/15/agfaphoto-af5105ms-and-af5135ms-worlds-first-hd-digital-photo-frames/

What could influence that at my site there are almost always 4 links and as on above examples 3 links ? Is it site font size ? Quality of site/content ?

Thank you for any help.

 

The number of the number of links shown there depends on various factors like page's content, the country from which the traffic comes and so on. So if you see three links, others might see four and vice-versa. Either way, you can't influence that number by yourself.

 

yes, it's 1, 2, 3 or 4 links in this big box, you can't choose.

 

Thank you for replies and help. So I cant influence it in any way.. thanks I thought that page font size may influence it.