NoMethodError in StoreController#add_to_cart

I am building the Depot app from Agile. And an hoping someone can point out the obvious that I cannot see.

** Here is the error - it occurs when I choose the "add to cart" link.

NoMethodError in StoreController#add_to_cart

You have a nil object when you didn't expect it! You might have expected an instance of Array. The error occured while evaluating nil.<<

RAILS_ROOT: ./script/../config/..

#{RAILS_ROOT}/app/models/cart.rb:11:in `add_product' #{RAILS_ROOT}/app/controllers/store_controller.rb:15:in `add_to_cart'

** controllers/store_controller.rb

class StoreController < ApplicationController

  def index     @products = Product.salable_items   end

  def add_to_cart      product = Product.find(params[:id])      @cart = find_cart      @cart.add_product(product)      redirect_to(:action => 'display_cart')   end

  def display_cart      @cart = find_cart      @item = @cart.items   end

  private   def find_cart      session[:cart] ||   end


** models/cart.rb

class Cart    attr_reader :items    attr_reader :total_price

   def intialize      @items =      @total_price = 0.0    end

   def add_product(product)       @items << LineItem.for_product(product)       @total_price += product.price    end end

** models/line_item.rb

class LineItem < ActiveRecord::Base

   belongs_to :product

   def self.for_product(product)       item =       item.quantity = 1       item.product = product       item.unit_price = product.price       item    end end.

Thanks -Stephen

Fred - THANKS! I have been looking at this for too many hours.