Double nested model forms

I am still having problems with nested forms. Here is my form code:

<%= form_for @account do |f| %>

<%= f.label :account_type %><br />
<%= f.text_field :account_type %><br />

    <%= f.fields_for :organizations do |builder| %>
        <%= builder.label :name %><br />
        <%= builder.text_field :name %><br />
        <%= builder.label :website %><br />
        <%= builder.text_field :website %><br />

        <%= f.fields_for :locations do |builder| %>
            <%= builder.label :phone %><br />
            <%= builder.text_field :phone %><br />
            <%= builder.label :toll_free_phone %><br />
            <%= builder.text_field :toll_free_phone %><br />
            <%= builder.label :fax %><br />
            <%= builder.text_field :fax %><br />
        <% end %>
    <% end %>

<%= f.submit "Add account" %>
<% end %>

The Account model:

class Account < ActiveRecord::Base

has_many :organizations

accepts_nested_attributes_for :organizations
end

The Organization model:

class Organization < ActiveRecord::Base

belongs_to :account

has_many :locations

accepts_nested_attributes_for :locations
end

And the Location model:

class Location < ActiveRecord::Base

belongs_to :organization

end

And lastly, the Accounts Controller:

class AccountsController < ApplicationController

def new
    @account = Account.new
    organization = @account.organizations.build
    organization.locations.build

    @header = "Create account"
end

def create
    @account = Account.new(params[:account])
    if @account.save
        #handle success
    else
        render 'new'
    end
end
end

Here is the error I am gett