Signing in a user - Chapter 8.2 of Michael Hartl's RoR Tutorial

I'm going through section 8.2 Michael Hartl's RoR 3.2 tutorial and
can't seem to get a user signed in. I've followed the tutorial
exactly, but for some reason @current_user appears to be blank when I
debug and print it out on a view after submitting the sign in form.
I've looked over the code multiple times and can't seem to find
anything wrong. Any help appreciated. Thank you.

(See below for code)