Hi Paul,
It sounds like we should be doing a better job of handling the "no results" situation, but here's why you aren't seeing anything.
By default, our site searches its local product database. This is because Amazon restricts the number of requests we can make to their API for product lookups, and we need all of the quota for updating products, so we can't send every user search through the API.
But you'll notice on the regular search results page, there's a notice about how the page searches our local database. This notice contains a link that takes you to the API search page, which is the best place to search if you can't find anything in our local search.
For example, this has plenty of results because it's an API search:
http://uk.camelcamelcamel.com/search?sq=Rinko+Kawauchi
Now that we've searched via the API, those products will soon appear in our local search results.
I guess the smart thing for the site to do would be to automatically redirect users to the API search page if there are no local results?