monthly permalink issue

Hi,

I have implemented a hack in the general templates function that outputs monthly links per category in the sidebar of the category archive. The related URL looks like this. And it works.

http://domain.com/wordpress/?m=200702&cat=16

However, the permalinks don’t work with this modification, regardless of the link structure I choose.

I even used /%category%/%year%/%monthnum%/%postname%/ to help, but even there I get a 404 for the URL

http://domain.com/wordpress/[category16]/2007/02/

Any help with that?