rake db:migrate (mysql) [duplicate]

Possible Duplicate:
Library not loaded: libmysqlclient.16.dylib error when trying to run 'rails server' on OS X 10.6 with mysql2 gem

Why i get this error?? What's means?

i have installed mysql2 gem, "sudo gem install mysql2"

Gemfile:

gem 'mysql2'

~: rake db:migrate --trace

rake aborted!
dlopen(/Library/Ruby/Gems/1.8/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle, 9): Library not loaded: libmysqlclient.18.dylib
  Referenced from: /Library/Ruby/Gems/1.8/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle
  Reason: image not found - /Library/Ruby/Gems/1.8/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle
/Library/Ruby/Gems/1.8/gems/mysql2-0.3.11/lib/mysql2/mysql2.bundle
/Library/Ruby/Gems/1.8/gems/mysql2-0.3.11/lib/mysql2.rb:9
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `require'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `require'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `each'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `require'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `each'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `require'
/Library/Ruby/Gems/1.8/gems/bundler-1.0.21/lib/bundler.rb:122:in `require'
/Users/leonardo/dev/myproject/config/application.rb:7
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:36:in `gem_original_require'
/Library/Ruby/Site/1.8/rubygems/custom_require.rb:36:in `require'
/Users/leonardo/dev/myproject/Rakefile:5
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/rake_module.rb:25:in `load_rakefile'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:501:in `raw_load_rakefile'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:82:in `load_rakefile'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:81:in `load_rakefile'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:65:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:133:in `standard_exception_handling'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/lib/rake/application.rb:63:in `run'
/Library/Ruby/Gems/1.8/gems/rake-0.9.2.2/bin/rake:33
/usr/bin/rake:19:in `load'
/usr/bin/rake:19

Put this bit of code in your .profile and .bash_profile files. If you don't know how to do that, type this in the terminal every time you open it...

export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$DYLD_LIBRARY_PATH"

This is what my .bash_profile looks like:

alias ll="ls -lahG"  
alias whereami="pwd"

export PATH="/Applications/MAMP/bin:/usr/local/bin:/usr/local/sbin:usr/local/my$
export DYLD_LIBRARY_PATH="/usr/local/mysql/lib:$DYLD_LIBRARY_PATH"

To edit your bash, in the root ($) terminal menu, type in ls -la, then type in nano .bash_profile and/or nano .profile to get into the text editor for the bash (I just keep them both the same, it might be redundant I don't know).

Once you're done with editing, hit ctrl-X, then 'return' to get back to the main menu, so to speak.