require 'icalendar' causes error

Hello,

I'm relatively new to Ruby-on-Rails.

I need to use an Icalendar event in my web app.

First, I installed the icalendar gem like so:

gem install icalendar

I then run the gem list command, and it indicates the gem is installed.

However, I can't actually use the gem anywhere.  if I do something like

event = Icalendar::Event.new

I get the error that Icalendar is an unintialized constant.

If I try to include icalendar within a class like so...

require 'icalendar'

I get the error

MissingSourceFile:  no such file to load -- icalendar

any suggestions?

Thanks in advance,
Tim