[Rails I18n] Globalizing Currency... last line

it's quite running smoothly...  at least  I get correct prices in local format...

but I cannot yet create or update it :

my Product model is defined as following :

class Product < ActiveRecord::Base

  composed_of :price, :class_name => "Globalize::Currency", :mapping => [ %w(price cents) ]

  attr_accessor :lp  #not stored in DB, used to display formatted price in form

the form as following :

<p><label for="">Prix (en euros)</label><br/>

<%= text_field 'product', 'lp'  %></p>

and the controller

 def new

    @product = Product.new

    @product.price = Currency.parse(0).format

  end

  def create

    @product = Product.new(@params[:product])

    if @product.save

.....

 def edit

    @product = Product.find(@params[:id])

    @product.lp = @product.price.format

   end

  def update

    @product = Product.find(@params[:id])

    @product.price =  Currency.parse(@params[:lp])

    if @product.update_attributes(@params[:product])

.....

   else

      render_action 'edit'

    end

end

when trying to create a new Product

I get the message :  undefined method `cents' for "0,00 €":String

when modifying an existing price in DB

.... there is no update !  

what's wrong... ??

thanks

kad