shastalasta on "[Plugin: Sermon Manager] getting 404 when clicking on series within sermon"

I can't seem to figure out why when I click on a series link within the sermon, it leads me to a 404? I've created the series and added the sermon to it, but it doesn't seem to think it exists. Any ideas?

http://corvallis4.org/sermons/7-defining-moments-part-2/

https://wordpress.org/plugins/sermon-manager-for-wordpress/