Can't seem to instantiate Builder::XmlMarkup.new?

I am unable to instantiate the Builder::XmlMarkup.new on one development machine ( Windows ) and upon my CentOS server. When I run the same code on my Ubuntu 8.10 VMWare machine, everything runs great?

In the Builder documentation ( http://builder.rubyforge.org/ ) it shows to put this at the top of the controller;

require 'rubygems' require_gem 'builder'

but this causes the controller to fail when it opens. I've locally installed the 'Builder' gem although this doesn't exist in my Linux stack and runs fine. Here's the details on the GEM I installed; gem = "Builder" by jim@weirichhouse.org at http://onestepback.org/

Does ActiveRecord ( as of 2.2.2 ) now have this feature? If so, why can't my controller create an instance of this class?

David