ActiveScriptRubyではじめてgemつかってみて
以下のようにしたらうまくいかないんですけど
なにがいけないのでしょうか
C:\Ruby>gem install mechanize
Updating metadata for 4 gems from http://gems.rubyforge.org/
....
complete
Building native extensions. This could take a while...
ERROR: Error installing mechanize:
ERROR: Failed to build gem native extension.

C:/Ruby/bin/ruby.exe extconf.rb install mechanize
checking for stdio.h... no
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of
necessary libraries and/or headers. Check the mkmf.log file for more
details. You may need configuration options.

Provided configuration options:
省略
Gem files will remain installed in C:/Ruby/lib/ruby/gems/1.8/gems/hpricot-0.6.16
1 for inspection.
Results logged to C:/Ruby/lib/ruby/gems/1.8/gems/hpricot-0.6.161/ext/fast_xs/gem
_make.out