Well, not so fast.
Something odd is going on.
The plugin is working in some places and not others.
http://ditchingsuburbia.com/newsletter - this one works fine (either modified or unmodified with your updated code).
http://ditchingsuburbia.com/books - works here also.
I’ve had a subscription form on all blog posts etc - but those aren’t working now (and I can’t say for sure they ever were…I don’t know if I tested it everywhere).
I’ve removed the subscription forms from the blog posts for the moment since I don’t want people trying to subscribe and not being able to.
It seems to work in one-template template groups like /book and /newsletter.
It doesn’t work in template groups like /about where one template displays >1 entry or in the blog on the single-entry blog template.
I can post my htaccess file if that might be it. It’s pretty much EL’s index.php removal, some redirects due to a domain name change, and setting the expires headers to make Google Page Speed happy.