failed render errors in controller

My image size check, doesn't work right. it works in update action, but doesn't work in create Maybe problem is .build(real_params)

I have model real estate

has_many :pictures, dependent: :destroy
validate  :picture_size

def picture_size
  pictures.each do |img|
    if img.image_file_size > 5.megabytes
      errors.add(:pictures, "should be less than 5MB")
    end
  end
end

Controller with update and create actions

  def update
  @user = current_user
  @real = RealEstate.find(params[:id])

  if @real.update(real_params)
    if params[:images]
      # The magic is here ;)
      params[:images].each do |image|
        @real.pictures.create(image: image)
      end
    end
  redirect_to root_path
else
render 'edit'
end
end

end

def create
@user = current_user
@real = current_user.real_estates.build(real_params)

if @real.save
  if params[:images]
    # The magic is here ;)
    params[:images].each do |image|
        @real.pictures.create(image: image)
    end
  end

  #flash[:success] = "Real Estate created!"
  redirect_to root_path
else
  render 'real_estates/new'
end
end

This is my errors render

<% if object.errors.any? %>
<div id="error_explanation">
<div class="alert alert-danger">
  The form contains <%= pluralize(object.errors.count, "error") %>.
</div>
<ul>
<% object.errors.full_messages.each do |msg| %>
  <li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>