Ruby on Rails 1.9.3 - Through View model is not getting update after adding one extra field to model

I am trying to implement the Optimistic Locking for Race Condition. For that, I added an extra column lock_version in the Product: Model through migration. And passing to through attr_accessible :lock_version. I am able to update model through the rails console, however, through View I am not able to update the model.

Product: Model's new field:

#  lock_version                       :integer(4)      default(0), not null

Passing lock_version in Product: Model:

 attr_accessible :lock_version

Pass it as hidden_field in View/edit:

form.hidden_field :lock_version

Product: Model Controller:

 def update
   ...
  @product.update_with_conflict_validation(params[:car])
 end

Inside Product: Model:

  def update_with_conflict_validation(*args)
    update_attributes(*args)
  rescue ActiveRecord::StaleObjectError
    errors.add :base, "This record changed while you are editing."
    false
  end

I am using Ruby Version

Loading development environment (Rails 3.2.22.4)
irb(main):001:0> RUBY_VERSION
=> "1.9.3"

Please let me know why I am not able to update model through UI/View, however, able to update through rails console.

Reference: https://www.youtube.com/watch?v=dcfP37d8-ZI