[Mongrel] mongrel_service install error

[Vapor ..]

when I run 'gem install mongrel_service'..it gives following error...

Building native extensions.  This could take a while...
ERROR:  Error installing mongrel_service:
        ERROR: Failed to build gem native extension.

c:/ruby/bin/ruby.exe extconf.rb install mongrel_service
checking for RegisterServiceCtrlHandlerEx()... no
checking for EnumServicesStatusEx()... no
checking for QueryServiceStatusEx()... no
creating Makefile


Gem files will remain installed in
c:/ruby/lib/ruby/gems/1.8/gems/win32-service-
0.5.2 for inspection.
Results logged to
c:/ruby/lib/ruby/gems/1.8/gems/win32-service-0.5.2/gem_make.out
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