WP Super Cache – Not caching, please help

Hi

I have a new blog. I am trying to use WP Super Cache, as it takes about 6 seconds to generate a page otherwise which is verging on people leaving 🙁

I have tried installing the plugin automatically, and manually. It does generate the cached page, but it generates it every time which is pretty pointless.

e.g.
<!– Dynamic page generated in 6.128 seconds. –>
<!– Cached page generated by WP-Super-Cache on 2009-07-24 22:58:01 –>

The site is:
http://www.jonhassall.com/articles/

I appreciate any help people can give me, thanks.