Module showing up in different positions

I have assigned two modules (Jazz Spotligts & Google Ads) to the right_top position. On most pages it shows up correctly.

Example:
http://jazzrevue.com/index.php?option=c ... Itemid=121

However, on a few pages the modules shows up at the bottom of the page. Example: http://jazzrevue.com/index.php?option=c ... &Itemid=27

What could cause these modules to go to the wrong position?

Hi

It's clearly a validation issue. Look: http://validator.w3.org/check?uri=http% ... ne&group=0

Check articles displaying on this page if the HTML code inside has been placed ok.