Can I Route YYYY/MM/DD URL Segments to a Controller?

[eluser]kirkaracha[/eluser]
I'm trying to use routes to have a timeline controller handle URLs like this: example.com/2011/04/15

I tried these routes, but they aren't working (I get a 404):

Code:

$route['(:num)/(:num)/(:num)'] = 'timeline/$1/$2/$3'; //  year, month, and day
$route['(:num)/(:num)'] = 'timeline/$1/$2'; // year and month
$route['(:num)'] = 'timeline/$1/'; // year only

What am I missing?