Ok that section looks correct, that's what you need to have in there, but apparently some other changes need to be made elsewhere for it to work (especially if you have other mods installed? The Google spidering one?!?).
At a minimum, you'll need to post postlist.tmpl here for me to help you any further.
Also, could you post a URL to the forums so that I can see what kind of URL structure you're using?
