data not saved in nested table with hidden (array) field passed

when I submit the form :

Parameters: {"authenticity_token"=>"LJ/ZME2lHZ7VwCDgPKX6OFe326fXSXo5UB4M0cPwbCE=", "project_id"=>"second", "utf8"=>"✓", "commit"=>"Add Todo", "esthour"=>{"rfp_id"=>"2", "cms_est_hours"=>"", "modul1hours_attributes"=>{"0"=>{"module_est_hours"=>"11", "modul1_id"=>"3"}, "1"=>{"module_est_hours"=>"111", "modul1_id"=>"4"}}, "designpages_est_hours"=>"", "ecommerce_est_hours"=>""}}

models

class Esthour < ActiveRecord::Base
  has_many :modul1hours
  accepts_nested_attributes_for :modul1hours
end

class Modul1hour < ActiveRecord::Base
  belongs_to :esthour
  attr_accessible :module_est_hours,:module_act_hours,:modul1_id,:esthour_id
end

view

<% @m1.map(&:id).each do |id|%>

  <%= b.fields_for :modul1hours, @esthour.modul1hours.build do |f| %>

    <%= f.hidden_field :modul1_id, :value => id %>

    <%= f.text_field :module_est_hours, :size => 30 %>
    </tr>
  <% end %>

<% end %>

controller

def new
  @esthour = Esthour.new
  @project = params[:project_id]
  respond_to do |format|
    format.html # new.html.erb
    format.json { render :json => @esthour }
  end
end

You can see my earlier question regarding this.

I'm waiting for valuable reply. Thanks.