link_to_remote problem

view:
<%= link_to_remote "#{post.title}", :url => { :controller=>:threads,
:action=>:show_content, :id=>post.id} %>

controller:
def show_content
    @post = Post.find_by_id params[:id]
    respond_to do |format|
          format.html { redirect_to_index}
          format.js
      end
  end

rjs:
page.replace_html "#{@post.id}_content", " dsf", :object => @post

When I click on the link_to_remote, I get RJS error [Object error]. The
link I click is id "364_content", and the error is
"Element.update('364_content', 'dsf')"

What's the problem? =|

Thanks!!

Oh yah, and here's what I'm trying to update:
for post in @posts...
...
<div id="#{post.id}_content"></div> in the view.
...