$route['404_override'] - why don't random URLs generate 404's ?

[eluser]stormbytes[/eluser]
I'm using the 'new' routing feature - $route['404_override'].

If I understand correctly, this should re-route any request that's returned 404 to the state URL.

But when I enter some address...

http://site-root/some/made/up/url

I get an error page like this:

Code:

An Error Was Encountered

Unable to load your default controller. Please make sure the controller
specified in your Routes.php file is valid.

[eluser]toopay[/eluser]
What CI version you are using?