URI Routing not working properly

[eluser]Emkay[/eluser]
I am using the following routing rules

Code:

$route['(:any)-(:num)'] = "category/$2";
$route['(:any)-(:num)/(:any)-(:num)'] = "listing/$4";

While the first one works just fine, the second rule does not.

For example,

Code:

www.website.com/books-5/

works, while

Code:

www.website.com/books-5/Engineering-Thermodynamics-102451

does not. It just leads me to a not found error, when in fact the rerouting url would be valid if it was routing correctly.

Can anyone pinpoint the problem?