Custom validation method issues

gistfile1.rb

class Item < ActiveRecord::Base
  attr_accessible :description
 
  validate :description_check, :on => create, :if => details?
  validate :description_check, :on => update
 
private
  def details?
    current_step == "details"
  end

  def description_check
    description_test = description.gsub(/[[:space:]\:\w\(\)\-\%\!\_\.\,\"\'\&\/\#\$]+/, "")
    errors.add(:base, description_test) unless description_test.nil? || description.test.empty?
  end
end