My Android tells me I need a reader when I try to read a book

I just installed Calibre Companion on Android and I got it to transfer a book over wifi from Calibre, but when I try to read the book, it gives me an error message saying I need a reader. That seems kinda odd because Calibre Companion is a reader.

Any ideas what I do next?

JFTR, I have a Nexus 7 & Android 4.2.2 with everything set to auto update.