Ruby on Rails

def create_permalink
  self.permalink = "#{self.name} #{self.brand.name}".parameterize
end

My product factory looks like this:

Factory.define :product do |p|
  p.sequence(:name) { |n| 'Product Name #{n}'}
  p.gender 'Man'
  p.sequence(:price) { |n| 123.00 + n }
  p.product_url 'http://www.example.com/prod-url'
  p.association :reseller
  p.association :subcategory
end

Then when I try to use the factory in Rspec, like this:

Factory.create(:product)

I get the following error:

Failure/Error: Factory.create(:product)
NoMethodError: undefined method `name' for nil:NilClass

Why is that?

Regards
Linus