Estoy intentando instalar la gema mysql2 en windows 7 Descargué el conector del sitio mysql y coloqué el archivo libmysql.dll en ruby200 \ bin

entonces hacer gema instalar mysql2

Estos son los resultados que estoy siendo tenue aquí?

Temporarily enhancing PATH to include DevKit...
Building native extensions.  This could take a while...
ERROR:  Error installing mysql2:
        ERROR: Failed to build gem native extension.

    C:/Ruby200/bin/ruby.exe extconf.rb
checking for rb_thread_blocking_region()... yes
checking for rb_wait_for_single_fd()... yes
checking for rb_hash_dup()... yes
checking for rb_intern3()... yes
*** 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:/Ruby200/bin/ruby
        --with-mysql-dir
        --without-mysql-dir
        --with-mysql-include
        --without-mysql-include=${mysql-dir}/include
        --with-mysql-lib
        --without-mysql-lib=${mysql-dir}/
extconf.rb:37:in `<main>': undefined method `[]' for nil:NilClass (NoMethodError
)


Gem files will remain installed in C:/Ruby200/lib/ruby/gems/2.0.0/gems/mysql2-0.
3.13 for inspection.
Results logged to C:/Ruby200/lib/ruby/gems/2.0.0/gems/mysql2-0.3.13/ext/mysql2/g
em_make.out