flash[;notice] not display after redirection

I read all previous posts about the same subject in Devise group but
couldn't find any answer, so iy may not be related to Devise , so
I debugged it ..
.
class Users::RegistrationsController <
Devise::RegistrationsController
..
      # POST /resource/sign_up
  def create
    build_resource
    if resource.save
      if resource.active?
        set_flash_message :notice, :signed_up
        sign_in_and_redirect(resource_name, resource)
      else
        set_flash_message :notice, :inactive_signed_up, :reason =>
resource.inactive_message.to_s
        debugger
        expire_session_data_after_sign_in!
        redirect_to after_inactive_sign_up_path_for(resource)
      end
    else
      clean_up_passwords(resource)
      render_with_scope :new
    end
  end

the flash notice is set ... I checked it in the console:

/users/registrations_controller.rb:27
expire_session_data_after_sign_in!
(rdb:2) flash {:notice=>"You have signed up successfully. However, we could not sign

you in because your account is unconfirmed."}

hiwever when the home page is displayed ... ( layout code ..)
                                                #content_wrapper
                                                        #content

%p.notice

= flash.to_yaml

= notice

%p.alert

= alert

Hi, I'm not an expert, I read through twice, and it's seems okay for
me, mostly if it works from console. It might be a bug. Report it I
think, or write to Rails Core Google Group.