error with the DB?

rake db:migrate

(in C:/Documents and Settings/Administrador/My Documents/Aptana Studio/
batataonrails)
rake aborted!
undefined method `each' for #<Mysql:0x3522530>

(See full trace by running task with --trace)
C:/Ruby/bin/rake:19: [BUG] Segmentation fault
ruby 1.8.6 (2008-08-11) [i386-mswin32]

This application has requested the Runtime to terminate it in an
unusual way.
Please contact the application's support team for more information.

The db:migrate does not change the version.
Use aptana Studio, and Mysql 5.1

Ps: Sorry for my English