Adlink stopped showing

Any suggestions why?

[badass101]

I've got an adlink block in the template of my website which displays an AdLink block just above the content.
I set this up last week and the AdLink began to serve nice relevent headings straight away.
However, yesterday the AdLink on the front page of the site began to serve a message of:
View Ads About: [Input Box]

I've double checked my robots.txt to check I'm not blocking any bots to the page, and all seems to be ok.
Any ideas why this has happened, and how long it may take to come back to normal - it looks really bad and is loosing me clicks (and data to analyse how well these Adlinks work on my site).

Thanks!

[hunderdown]

AdSense throws that up periodically. It's possible that many viewers are NOT seeing it, even though you are.

It should go away on its own.