I'm setting up ZF with a typical dir structure to support modules, eg

application
__+ modules
_____+ default
________+ controllers
________+ views
_____+ mymodule
________+ controllers
________+ views

These all work, taking me to my default index controller:
http://photon
http://photon/index.php/default
http://photon/index.php/default/index

But these give me a 404:
http://photon/default
http://photon/default/index

In my bootstrapper, rather than using $front->setControllerDirectory() I'm using the more general

$front->addModuleDirectory('../application/modules');

so that I don't have to edit my bootstrapper every time I add a module.

I know I'm missing something really basic here, probably involving Zend_Controller_Router_Route, but for some reason I'm just not seeing it. Can anyone point out what I'm missing?

thanks,
Eric