help in watir

[sathya_k_83]

hi
I have installed Ruby 1.8.5-21 and also installed the watir 1.5.0 gem.
when i use the below statement
require 'watir' #i get the below error
Operating Systems :Windows XP


require 'watir' #i get the below error
# use watir gem
test_site = 'http://www.google.com' # set a variable
ie =Watir::IE.new # open the IE browser
ie.goto(test_site) # load url, go to site
ie.text_field(:name, "q").set("pickaxe") # load text "pickaxe" into search field named "q"
ie.button(:name, "btnG").click # "btnG" is the name of the Search button, click it

if ie.text.include?("Programming Ruby")
puts "Test Passed. Found the test string: 'Programming Ruby'."
else
puts "Test Failed! Could not find: 'Programming Ruby'"
end


i get the below error

./watir.rb:4: uninitialized constant Watir (NameError)
from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `gem_original_require'
from c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in `require'
from watir.rb:2
>Exit code: 1

please tell me how to prevent this error.

Thanks in Advance
K Sathya Narayanan