I'm trying to get FactoryGirl to generate some names for me, but the sequence doesn't seem to increment.

```
# spec/factories/vessel.rb
require 'factory_girl'
FactoryGirl.define do

  sequence :vessel_name do |n|
    "TK42#{n}"
  end

  factory :vessel do
    name FactoryGirl.generate(:vessel_name)
    vessel_type 'fermenter'
    volume_scalar 100.0
    volume_units 'bbl'
  end
end

```

---

```
# spec/models/vessel_spec.rb
require 'spec_helper'

describe Vessel do

  context 'working in the factory' do

    it 'makes a valid vessel' do
      vessel = FactoryGirl.create(:vessel)
      vessel.should be_valid, "Invalid vessel #{vessel.valid? || vessel.errors.messages.inspect}"
    end

    it 'makes another valid vessel' do
      vessel = FactoryGirl.create(:vessel)
      vessel.should be_valid, "Invalid vessel #{vessel.valid? || vessel.errors.messages.inspect}"
    end

  end

end

```

The spec output is

```
Vessel
  working in the factory
    makes a valid vessel
    makes another valid vessel (FAILED - 1)

Failures:

  1) Vessel working in the factory makes another valid vessel
     Failure/Error: vessel = FactoryGirl.create(:vessel)
     ActiveRecord::RecordInvalid:
       Validation failed: Name has already been taken
     # ./spec/models/vessel_spec.rb:13:in `block (3 levels) in <top (required)>'

```

---

```
# app/models/vessel.rb
class Vessel < ActiveRecord::Base

  attr_accessible :name, :vessel_type, :volume_scalar, :volume_units

  validates :name, :presence => true, :uniqueness => true

end

```

---

```
0 HAL:0 work/nrb-brewery-management % bundle show factory_girl_rails rspec
/home/brundage/.rvm/gems/ruby-1.9.3-p0/gems/factory_girl_rails-3.5.0
/home/brundage/.rvm/gems/ruby-1.9.3-p0/gems/rspec-2.11.0

0 HAL:0 work/nrb-brewery-management % rails c test
Loading test environment (Rails 3.2.6)
1.9.3p0 :001 > FactoryGirl.generate :vessel_name
 => "TK422" 
1.9.3p0 :002 > FactoryGirl.generate :vessel_name
 => "TK423" 
1.9.3p0 :003 > FactoryGirl.generate :vessel_name
 => "TK424" 
1.9.3p0 :004 > FactoryGirl.generate :vessel_name
 => "TK425" 

```

Why doesn't FactoryGirl generate a sequence of names in my spec?