Ruby on Rails: Thinking Sphinx Delayed Delta Isn't Working by Following Documentation

Question

Following the delayed delta guide here (at the bottom) I did everything that the documentation asked. After I did all of the steps there, I ran a rake ts:rebuild and a rake ts:dd and attempted to load my app (development). When it loads, I get:

NameError in CustomersController#index

uninitialized constant ThinkingSphinx::Deltas::DelayedDelta

I've done rakes for dropping the db, setting it up, and stopping ts but to no avail. I'm using sphinx 0.9.9 r2117, thinking-sphinx 1.3.18, and ts-delayed-delta 1.1.0.

My index in my model.rb looks like this:

define_index do
    indexes :name, :match_mode => :any

    set_property :delta => :delayed
    has :id, created_at, updated_at
end

Have any ideas of what I'm doing wrong?

EDIT: I'm an idiot. I forgot to restart the server. Commence the downvotes.