acts as ferret installation

C:\Documents and Settings\Administrator>gem install acts_as_ferret Building native extensions. This could take a while... ERROR: Error installing acts_as_ferret:         ERROR: Failed to build gem native extension.

c:/ruby/bin/ruby.exe extconf.rb creating Makefile

nmake 'nmake' is not recognized as an internal or external command, operable program or batch file.

Gem files will remain installed in c:/ruby/lib/ruby/gems/1.8/gems/jk-ferret-0.11 .8.2 for inspection. Results logged to c:/ruby/lib/ruby/gems/1.8/gems/jk-ferret-0.11.8.2/ext/gem_make .out

i tried to install acts as ferret gem.. i already installed ferret 0.11.5 mswin32.. but when i give gem install acts_as_ferret, i got the above error.. eventhough i downloaded nmake.exe.. after that also i get this error.. please somebody help me to install acts_as_ferret gem..

is nmake.exe in your PATH?