Redmine

I have been using the SVN version of redmine for some time, here is my ruby version:

About your application's environment
Ruby version 1.8.7 (i486-linux)
RubyGems version 1.3.5
Rack version 1.0
Rails version 2.3.5
Active Record version 2.3.5
Active Resource version 2.3.5
Action Mailer version 2.3.5
Active Support version 2.3.5
Environment production
Database adapter mysql
Database schema version 20101114115359

Whenever i try set a user as developer, i get this error:

Processing UsersController#edit_membership (for xx.xx.xx.xx at 2011-01-22 08:04:55) [POST]
Parameters: {"commit"=>"Add", "membership"=>{"project_id"=>"1", "role_ids"=>["4"]}, "action"=>"edit_membership", "authenticity_token"=>"lF3bD0pOqrhBQKWbImpX2qL+Bhy/osgO4+njjAkNt+k=", "id"=>"60", "controller"=>"users", ""=>""}

ActiveRecord::StatementInvalid (Mysql::Error: Column 'role_id' cannot be null: INSERT INTO `members` (`created_on`, `project_id`, `role_id`, `user_id`, `mail_notification`) VALUES):
app/controllers/users_controller.rb:191:in `edit_membership'
public/dispatch.fcgi:26_

I have tried huntdown if its a code issue or a wrong mysql tabel, but i dont have much experience with ruby, any ideas?