Usei o ruby 1.9.2 e o rails 3.0.3. iam tentando instalar rmagick gem, mas quando eu corrobundle install Eu recebi um erro me diz:

Installing rmagick (2.12.1) with native extensions c:/Ruby192/lib/ruby/site_ruby
/1.9.1/rubygems/installer.rb:529:in `rescue in block in build_extensions': ERROR
: Failed to build gem native extension. (Gem::Installer::ExtensionBuildError)

       c:/Ruby192/bin/ruby.exe extconf.rb
checking for Ruby version >= 1.8.5... yes
checking for stdint.h... *** 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:
       --with-opt-dir
       --without-opt-dir
       --with-opt-include
       --without-opt-include=${opt-dir}/include
       --with-opt-lib
       --without-opt-lib=${opt-dir}/lib
       --with-make-prog
       --without-make-prog
       --srcdir=.
       --curdir
       --ruby=c:/Ruby192/bin/ruby
c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:368:in `try_do': The complier failed to genera
te an executable file. (RuntimeError)
You have to install development tools first.
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:452:in `try_cpp'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:834:in `block in have_header'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:693:in `block in checking_for'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:280:in `block (2 levels) in postp
one'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:254:in `open'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:280:in `block in postpone'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:254:in `open'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:276:in `postpone'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:692:in `checking_for'
       from c:/Ruby192/lib/ruby/1.9.1/mkmf.rb:833:in `have_header'
       from extconf.rb:171:in `<main>'


Gem files will remain installed in c:/Ruby192/lib/ruby/gems/1.9.1/gems/rmagick-2
.12.1 for inspection.
Results logged to c:/Ruby192/lib/ruby/gems/1.9.1/gems/rmagick-2.12.1/ext/RMagick
/gem_make.out
       from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:507:in `b
lock in build_extensions'
       from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:482:in `e
ach'
       from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:482:in `b
uild_extensions'
       from c:/Ruby192/lib/ruby/site_ruby/1.9.1/rubygems/installer.rb:156:in `i
nstall'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/sour
ce.rb:96:in `install'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/inst
aller.rb:55:in `block in run'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/spec
_set.rb:12:in `block in each'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/spec
_set.rb:12:in `each'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/spec
_set.rb:12:in `each'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/inst
aller.rb:44:in `run'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/inst
aller.rb:8:in `install'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/cli.
rb:226:in `install'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/vend
or/thor/task.rb:22:in `run'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/vend
or/thor/invocation.rb:118:in `invoke_task'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/vend
or/thor.rb:246:in `dispatch'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/lib/bundler/vend
or/thor/base.rb:389:in `start'
       from c:/Ruby192/lib/ruby/gems/1.9.1/gems/bundler-1.0.10/bin/bundle:13:in
`<top (required)>'
       from c:/Ruby192/bin/bundle:19:in `load'
       from c:/Ruby192/bin/bundle:19:in `<main>'

Eu instalei o ruby dehttp://rubyinstaller.org/downloads/ com kit de desenvolvimento e a versão mais recente do ImageMagick. Tentei definir configurações do rmagick (lib e incluir diretórios), mas ainda assim recebo o mesmo erro

qualquer ajuda? Quaisquer pensamentos para resolver o problema?