The specified procedure could not be found - Init_win32api (LoadError)

Hi All,
    I just installed Ruby1.8.6 using One step installer and installed
following gems in order
- rspec
- watir
- dbi

In one my script i use - require 'win32api'

When I run this script I get the following error.

C:/ruby/lib/ruby/1.8/i386-mswin32/win32api.so: 127: The specified
procedure could not be found. - Init_win32api (LoadError)
C:/ruby/lib/ruby/1.8/i386-mswin32/win32api.so from C:/ruby/lib/ruby/
site_ruby/1.8/rubygems/custom_require.rb:31:in `require'
        from ./XSSTesting_spec.rb:9
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/example_group_runner.rb:15:in `load'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/example_group_runner.rb:15:in `load_files'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/example_group_runner.rb:14:in `each'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/example_group_runner.rb:14:in `load_files'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/options.rb:94:in `run_examples'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/lib/spec/
runner/command_line.rb:9:in `run'
        from C:/ruby/lib/ruby/gems/1.8/gems/rspec-1.1.12/bin/spec:4
        from C:/ruby/bin/spec:19:in `load'
        from C:/ruby/bin/spec:19

I have no idea why this is failing. On my boxI have Visual Studio 2K5
installed. Not sure if is causing the problem. Please help me to get
rid of this issue.

Thanks,
Sushil. Karwa