update partial render form fields

Hi i have the following problem. I followed the screen cast to create
complex forms from railscats so i create a partial view for my
equipments list, so the client can add several different equipments, I
also made another view in case looking for the equipment inside the
select box. When i choose a equipment from the view (find_equipment) i
created there is no problem when there is only one equipment inside
the client form, but when I another equipment and I try to select it
from the select view (find_equipment) it does not update the select
box it should, it update the first select box.

I have a similar problem with observe_field, it should update the
properties for a certain product, but it only update the first select
list the other lists are not updated.

Here is the source code:

_equipment_services.html.erb
<div class="equipment">
  <% fields_for "voip[equipments_services_attributes]
[]",equipment_services do |e|%>
  <p class="titulo">Informaci&oacute;n Equipos</p>
  <p>
    Activo Fijo
    <
%=e.select("equipment_id",Equipment.find(:all,:conditions=>"estado=6",:order=>"numero_activo_fijo").collect{|
p>[p.numero_activo
_fijo, p.id]},:index=>nil)%>

        <% if equipment_services.new_record? %>
          <%="Estado Activo"%> <%=e.hidden_field("estado",:value=>6)
%>
          <%= link_to_function "Eliminar",
"this.up('.equipment').remove()" %>
        <%else%>
          <=% link_to_function "Eliminar",
"mark_for_destroy(this,'.contact')" %>
          <%= e.hidden_field(:id,:index=>nil) %>
          <%= "Estado" %>
          <%=
e.select("estado",Code.find(:first, :conditions=>["id=5"]).elements.collect{|
p> [p.descripcion,p.id]},:index=>nil) %>
          <%=
e.hidden_field(:should_destroy,:index=>nil, :class=>"should_destroy")
%>
        <%end%>
        <%=link_to "Crear Nuevo
Equipo",add_equipment_equipment_path,:popup =>
["Agregar_Nuevo_Equipo","height=600, width=700"]%>
        <%= link_to "Buscar Equipos",
{:action=>"find_equipment", :controller=>"show_select"}, :popup =>
["Show_Equipment","height=60
0, width=700"]%>
  </p>
<%end %>
</div>

javascript function
function set_value(id,value)
{
  opener.document.getElementById(id).value=value;
  window.close();
}

find_equipment.html.erb

<table>

  <tr>
    <% form_tag find_equipment_show_select_path, :method=>"get" do%>
      <td>Buscar Usuario:</td>
      <td><%=select_tag "busqueda","<option value='1'>Modelo</

<option value='2' selected='true'>N&uacute;mero Activo Fijo</op
<option value='3'>N&uacute;mero Serie</option><option

value='4'>Direcci&oacute;n MAC</option>"%>
      <td><%=text_field_tag :search, params[:search]%></td>
      <td colspan=3><%=submit_tag "Buscar", :name=>nil%></td>
     <%end%>
  </tr>
<tr>
  <th>Modelo</th>
  <th>Marca</th>
  <th>Activo Fijo</th>
  <th>N&uacute;mero de serie</th>
  <th> Tipo Equipo </th>
</tr>
<%
    switch=false
    for equipment in @equips
%>
  <tr class="<%= if switch
                   "TRPAR"
                else
                    "TRIMPAR"
                end %>
  <% switch=!switch %>">
    <td><%=equipment.modelo%></td>
    <td><%=Code.getDescripcion(equipment.marca)%></td>
    <td><
%=link_to_function("#{equipment.numero_activo_fijo}","set_value('voip_equipments_services_attributes__equipment_id','#{equi
pment.id}')")%></td>
    <td><%=equipment.numero_serie%></td>
    <td><%=Code.getDescripcion(equipment.code_id)%></td>
  </tr>
    <% end %>
</table>

Can anyone help me please? i'm kind of lost here