acts_as_cached missing

I can't seem to be able to get a very basic cache working on my user
model. I have the following in the user model

class User < ActiveRecord::Base
acts_as_cached :include => [:user_videos, :user_images, :user_interests,

than in the user_controller I have

  @user = User.get_cache(params[:id])

so far so good, right? if I run memcached -vv in interactive mode this
is what I see. The first hit, stores and the second one just serves up.

<1840 set app-development:User:6654 0 1800 2845


<1840 get app-development:User:6654

1840 sending key app-development:User:6654
1840 END

But in both the development.log and the mysql query log, I see database
calls being made (every time, not just the first time) against user,
user_videos, user_images, etc.