[Plugin: Query Multiple Taxonomies] QMT not working on 404 Page

I’m implementing the QMT plugin to filter a site with audio-recordings of sermons from a church (http://www.calvarybennett.org/listen-online/?page_id=11).

It works fine when it finds posts, but when it comes up empty it goes to a 404 page. That’s not necessarily a problem except for the fact that the plugin no longer works on the 404 page (example: http://www.calvarybennett.org/listen-online/?book=&service=sunday-am&speaker=pastor-jim).

Any ideas why it’s not working?

Thanks.

http://wordpress.org/extend/plugins/query-multiple-taxonomies/