gem install mysql failure in Snow Leopard

I successfully installed MySql x86_64 in Snow Leopard and Ruby and Ruby Gems seems to be installed properly: ``` $ which mysql /usr/local/mysql/bin/mysql $ which ruby /usr/bin/ruby $ which gem /usr/bin/gem $ mysql Your MySQL connection id is 404 Server version: 5.1.37 MySQL Community Server (GPL) $ ruby -v ruby 1.8.7 (2008-08-11 patchlevel 72) [universal-darwin10.0] $ gem -v 1.3.5 ``` Unfortunatly I get an error installing mysql gem: ``` $ sudo gem update --system ... $ sudo env ARCHFLAGS="-arch x86_64" gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config Building native extensions. This could take a while... ERROR: Error installing mysql: ERROR: Failed to build gem native extension. /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby extconf.rb --with-mysql-config=/usr/local/mysql/bin/mysql_config mkmf.rb can't find header files for ruby at /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/ruby.h Gem files will remain installed in /Library/Ruby/Gems/1.8/gems/mysql-2.8.1 for inspection. ```