When I type something in the address bar then I sometime see Opera offering pages which have the given word in the page text. This would be very useful if it worked all the time, but whenever I try it it fails to show pages which I know I've visited recently and I can clearly remember some words from the page.

Why is is that it only works for some pages? Is there a way to fix it? In its current form this feature is pretty much useless, because sometimes it works, but most often it doesn't.