problem with ActionController.add_renderer :txt and respond_with

the code..

Mime::Type.register "text/plain", :txt

ActionController.add_renderer :txt do |object, options|
  self.content_type ||= Mime::TXT
  self.response_body = object.inspect
end

class Goal < ActiveRecord::Base
  def to_s
    name
  end
end

class GoalsController < ApplicationController
  respond_to :html, :xml, :json, :yaml, :txt

  # GET /goals
  # GET /goals.xml
  def index
    @goals = Goal.all
    respond_with @goals
  end

  # GET /goals/1
  # GET /goals/1.xml
  def show
    @goal = Goal.find(params[:id])
    respond_with @goal
  end

class GoalsController < ApplicationController
  respond_to :html, :xml, :json, :yaml, :txt

  def index
    @goals = Goal.all
    respond_with @goals
  end

  def show
    @goal = Goal.find(params[:id])
    respond_with @goal
  end

  ...
end

results in..
Template is missing

Missing template goals/show with
{:formats=>[:txt], :handlers=>[:rjs, :rhtml, :rxml, :erb, :builder], :locale=>[:en, :en]}
in view paths "/home/rob/machine/app/views", "/home/rob/machine/vendor/
plugins/min_max_attribute/app/views", "/home/rob/machine/vendor/
plugins/map_attribute/app/views", "/home/rob/machine/vendor/plugins/
lib_ifit/app/views", "/home/rob/machine/vendor/plugins/dynamic_form/
app/views", "/home/rob/machine/vendor/plugins/attribute_bitmask/app/
views", "/home/rob/machine/vendor/plugins/acts_as_nested_set/app/
views", "/var/lib/gems/1.8/gems/devise-1.1.2/app/views"

so, how do I get this to work?
the :yaml example works...