Filter function in Dashboard doesn't work

Hello!

If I select ‘Pages’ in the Dashboard there is an option to filter the pages with the dropdown menue.

Somehow if I try to select a date he finds nothing at the moment.

http://www.wiseseo.de/wp-admin/edit.php?s&post_status=all&post_type=page&action=-1&m=201308&seo_filter&paged=1&action2=-1

If I delete the ‘s&’ after …edit.php? it works again.

http://www.wiseseo.de/wp-admin/edit.php?post_status=all&post_type=page&action=-1&m=201308&seo_filter&paged=1&action2=-1

The filter works in a new test installation, too, without any tweaks.

The problem for me is, that our support systems uses that filter function for tickets.

Maybe you can help me.

Thanks & regards,

Martin