I receive this error when running a rake command:

$ rake db:migrate
(in /Users/jeremy/rails/depot)
dyld: NSLinkModule() error
dyld: Library not loaded: /usr/local/mysql/lib/mysql/libmysqlclient. 
15.dylib
   Referenced from: /usr/local/lib/ruby/gems/1.8/gems/mysql-2.7/lib/ 
mysql.bundle
   Reason: image not found
Trace/BPT trap

I'm working with the book "Agile Web Development with Rails" and even  
though it discusses many possible errors, none of them relate to this  
one. Also, my database.yml file seems to be correct so I don't think  
that's the problem.