Display empty field if no results have been found during edit

Question

Hi, I'm trying to display an empty field when I edit a rows.

I have a machine table with ipvsix table.

Code in ipvsixes/_form :

 <% unless @machines.blank? %>
     <% f_machine.fields_for :ipvsixes do |f_ipv| %>
        <%= render :partial => 'ipvsixes/form', :locals => { :f_ipv => f_ipv } %>  
     <% end %>
 <% else %>
      empty ipv6
 <% end %> 

But instead of display empty ipv6 I would like have the fields to created it. And I do not really have idea about how create it.

Thanks in advance.