Error ala actualizar div con ajax la segunda vez

Hola
Tengo un formulario en el q subo una imagen y la muestro. La primera lo
hace bien pero el resto no…

Mi código es el siguiente:

Vista:

[…]

<%= render(:partial => 'form') %>
[..]

Partial _form.rhtml

[…]
<% form_for(:e_content, :url => {:controller => “e_contents”, :action =>
“suboLogo”, :templateID => params[:templateID] },
:html => { :multipart => true, :target => “upload_frame”}) do |form|%>

<%= flash[:errorlogo] %>
<%if !(photo.nil?)%> <%= image_tag(photo.public_filename, :size => "72x65")%> <%else%> <%= image_tag("../images/nologo.gif", :size => "72x65")%> <%end%>
  <%= image_submit_tag ("../images/aceptar.gif", :class => :submit ) %>

Cotrolador

[…]
respond_to do |format|
flash[:errorlogo] = ‘Su logo se ha subido correctamente.’
format.js do
responds_to_parent do
render :update do |page|
page.replace_html ‘logo’, :partial => ‘form’
end
end
end
end
[…]

Sabeís porqué puede ser??

Muchas gracias

Error que da en el log es esto:

Log

NoMethodError (You have a nil object when you didn’t expect it!
The error occurred while evaluating nil.call):
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/mime_responds.rb:163:in
respond' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/mime_responds.rb:161:ineach’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/mime_responds.rb:161:in
respond' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/mime_responds.rb:105:inrespond_to’
/app/controllers/establishment_contents_controller.rb:250:in
suboLogo' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:insend’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:1095:in
perform_action_without_filters' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:632:incall_filter’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:634:in
call_filter' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:619:inperform_action_without_benchmark’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
perform_action_without_rescue' c:/ruby/lib/ruby/1.8/benchmark.rb:293:inmeasure’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/benchmarking.rb:66:in
perform_action_without_rescue' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/rescue.rb:83:inperform_action’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:in
send' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:430:inprocess_without_filters’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/filters.rb:624:in
process_without_session_management_support' c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/session_management.rb:114:inprocess’
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/base.rb:330:in
process' c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/dispatcher.rb:41:indispatch’
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/webrick_server.rb:113:in
handle_dispatch' c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/webrick_server.rb:79:inservice’
c:/ruby/lib/ruby/1.8/webrick/httpserver.rb:104:in service' c:/ruby/lib/ruby/1.8/webrick/httpserver.rb:65:inrun’
c:/ruby/lib/ruby/1.8/webrick/server.rb:173:in start_thread' c:/ruby/lib/ruby/1.8/webrick/server.rb:162:instart’
c:/ruby/lib/ruby/1.8/webrick/server.rb:162:in start_thread' c:/ruby/lib/ruby/1.8/webrick/server.rb:95:instart’
c:/ruby/lib/ruby/1.8/webrick/server.rb:92:in each' c:/ruby/lib/ruby/1.8/webrick/server.rb:92:instart’
c:/ruby/lib/ruby/1.8/webrick/server.rb:23:in start' c:/ruby/lib/ruby/1.8/webrick/server.rb:82:instart’
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/webrick_server.rb:63:in
dispatch' c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/servers/webrick.rb:59 c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:ingem_original_require’
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
require' c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:inrequire’
c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:342:in
new_constants_in' c:/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:495:inrequire’
c:/ruby/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/commands/server.rb:39
c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:in
gem_original_require' c:/ruby/lib/ruby/site_ruby/1.8/rubygems/custom_require.rb:27:inrequire’
script/server:3

Rendering
c:/ruby/lib/ruby/gems/1.8/gems/actionpack-1.13.3/lib/action_controller/templates/rescues/layout.rhtml
(500 Internal Error)