Error running simple Markaby example

I have installed Markaby using gem, when I try running the example
code for Markaby...

$ ruby markaby.rb
./markaby.rb:5: uninitialized constant Markaby (NameError)
        from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in
`require'
        from markaby.rb:3

#markaby.rb
require 'markaby'

  mab = Markaby::Builder.new
  mab.html do
    head { title "Boats.com" }
    body do
      h1 "Boats.com has great deals"
      ul do
        li "$49 for a canoe"
        li "$39 for a raft"
        li "$29 for a huge boot that floats and can fit 5 people"
      end
    end
  end
  puts mab.to_s

Tony K. wrote:

I have installed Markaby using gem, when I try running the example
code for Markaby...

$ ruby markaby.rb
./markaby.rb:5: uninitialized constant Markaby (NameError)
       from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:21:in
`require'
       from markaby.rb:3

#markaby.rb
require 'markaby'

mab = Markaby::Builder.new
mab.html do
   head { title "Boats.com" }
   body do
     h1 "Boats.com has great deals"
     ul do
       li "$49 for a canoe"
       li "$39 for a raft"
       li "$29 for a huge boot that floats and can fit 5 people"
     end
   end
end
puts mab.to_s

Try using

require 'rubygems'

at the top of the script?

-Justin