any one use calendar_helper GEM?

I had been using the calendar_helper plugin previously which worked
fine. For my current project I decided to use the gem but am having
trouble getting it to work.

After install of the gem if I do:

require 'calendar_helper'

=> ["CalendarHelper"]

at the console it seems to load ok. However in the app when I do
require 'calendar_helper'
inlcude CalendarHelper

I am unable to get:
undefined method `calendar' for #<#<Class:0xb70ca910>:0xb70ca8e8>
in my view.

I tried require statement in environment.rb which is where I normally
load gems from as well as in the controller where I am using it. But I
get the same error.

Can some one help? Thank you,

bakki