ruby1.8.7 gtk2-0.90.7-x86-mingw32 エラー

gtk2-0.90.7-x86-mingw32を入れたけど

sampleのmain.rbにてlibgdk_pixbuf-2.0-0.dllからみつかりませんでした。のエラー

C:\ruby\Ruby187\lib\ruby\gems\1.8\gems\gtk2-0.90.7-x86-mingw32\sample\gtk-demo>gem list

*** LOCAL GEMS ***

atk (0.90.7 x86-mingw32, 0.90.2 x86-mingw32)

cairo (1.10.0 x86-mingw32)

gdk_pixbuf2 (0.90.7 x86-mingw32)

glib2 (0.90.7 x86-mingw32, 0.90.2 x86-mingw32)

gtk2 (0.90.7 x86-mingw32, 0.90.2 x86-mingw32)

pango (0.90.7 x86-mingw32, 0.90.2 x86-mingw32)

pkg-config (1.0.8)

rubygems-update (1.5.2)

C:\ruby\Ruby187\lib\ruby\gems\1.8\gems\gtk2-0.90.7-x86-mingw32\sample\gtk-demo>ruby -rubygems main.rb

C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `gem_original_require': no such file to load -- gtk2.so

(LoadError)

from C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `require'

from C:/ruby/Ruby187/lib/ruby/gems/1.8/gems/gtk2-0.90.7-x86-mingw32/lib/gtk2/base.rb:24

from C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `gem_original_require'

from C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:29:in `require'

from C:/ruby/Ruby187/lib/ruby/gems/1.8/gems/gtk2-0.90.7-x86-mingw32/lib/gtk2.rb:11

from C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:32:in `gem_original_require'

from C:/ruby/Ruby187/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:32:in `require'

from main.rb:11

C:\ruby\Ruby187\lib\ruby\gems\1.8\gems\gtk2-0.90.7-x86-mingw32\sample\gtk-demo>ruby -v

ruby 1.8.7 (2010-12-23 patchlevel 330) [i386-mingw32]

C:\ruby\Ruby187\lib\ruby\gems\1.8\gems\gtk2-0.90.7-x86-mingw32\sample\gtk-demo>