Silver007A on "Sticky posts not working"

Hi I'm using Wp 3.5.1 and the twenty eleven theme.

I've made a post sticky, but it doesn't seem to show. I've tried the Twenty Ten theme and others, but still no sticky.

I've checked it in other SP sites and it works OK. Just this site it won't-

http://www.isabels-typing-services.co.uk/blog/

Can anyone help please?

Thanks