multi level has_many through

hello,

how can i use has_many through for class further then 2 levels
i have 4 classes :
Product
StoreEntry
Store
StoreShippingCountry

and i try to access StoreShippingCountry from Product

what i do :

class Product < ActiveRecord::Base
  has_many :store_entries
  has_many :stores,
    :through => :store_entries
  has_many :store_shipping_countries,
    :through => :store_entries,
    :source => :stores
end

and here is the error i recieve :
Could not find the source association(s) :stores in model StoreEntry.
Try 'has_many :store_shipping_countries, :through
=> :store_entries, :source => <name>'. Is it one
of :issues, :store, :prices, :store_shipping_countries, :guarantees, :product,
or :actions?

Can someone help me?

Any answer to this? Or is it definitely not possible?

martin