Problem with character set utf8

Hi,

I have create an empty rails project on aptana;
I have manually, on PhpMyAdmin, create my database.
When i run rake db:migrate under Aptana, i have this message :

rake aborted!
NoMethodError: undefined method `ord' for 0:Fixnum: SET NAMES 'utf8'

Is anyone have an idea

Thanks

My config :
Windows XP Pro SP3
Wamp 2.0
Aptana 2.0.4
Ruby 1.8.6