rails - how to make a GET request to action with parameters

I'm hoping this problem is a fairly simple one as I am relatively new to rails development.
I am trying to make a get request from a controller with a specified action and pass required parameters. This is the relevant code in the helper class:

module ChartsHelper
   def chart_tag (action, height, params = {})
     params[:format] ||= :json
     path = charts_path(action, params)
     content_tag(:div, :'data-chart' => path, :style => "height: #{height}px;") do
       image_tag('loading.gif', :size => '32x32', :class => 'spinner')
   end
  end
 end
 

and the corresponding action in the ChartsController:

class ChartsController < ApplicationController
 
   def week_events_bar_chart
     days = (params[:days] || 30).to_i
     render :json => {
       :type => 'AreaChart',
       :cols => [['string', 'Date'], ['number', 'subscriptions']],
       :rows => (1..days).to_a.inject([]) do |memo, i|
         date = i.days.ago.to_date
         t0, t1 = date.beginning_of_day, date.end_of_day
         subscriptions = Kpsevent.all.count
         memo << [date, subscriptions]
         memo
       end.reverse,
       :options => {
         :chartArea => { :width => '90%', :height => '75%' },
         :hAxis => { :showTextEvery => 30 },
         :legend => 'bottom',
       }
     }
   end
 end
 

The routes file has the following:

resource :charts do
     get 'week_events_bar_chart'
 end
 

However I get the following output when trying to perform this request:

 Started GET "/charts.week_events_bar_chart?days=14" for 127.0.0.1 at Tue May 22 00:31:48 +1200 2012
    Processing by ChartsController#index as 
    Parameters: {"days"=>"14"}
 

And the controller action is never called.
Is anyone able to help with this problem?

EDIT: rake routes output:

week_events_bar_chart_charts GET    /charts/week_events_bar_chart(.:format) {:controller=>"charts", :action=>"week_events_bar_chart"}
 POST   /charts(.:format)                  {:controller=>"charts", :action=>"create"}
 new_charts GET    /charts/new(.:format)    {:controller=>"charts", :action=>"new"}
 edit_charts GET    /charts/edit(.:format)  {:controller=>"charts", :action=>"edit"}
 GET    /charts(.:format)                   {:controller=>"charts", :action=>"show"}
 PUT    /charts(.:format)                   {:controller=>"charts", :action=>"update"}
 DELETE /charts(.:format)                   {:controller=>"charts", :action=>"destroy"}
 

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