Not receiving form data using form_remote_for


I'm having a problem that I am sure there is a simple solution for, but
I can't see it.

I have the following partial:

<% form_for :time_entry,,
   :url => hash_for_time_entries_url(:period => @period, :action =>
   :html => { :id => 'time-entry-form' } do |f| %>
<table border="0" cellspacing="0" cellpadding="5" width="100%">
    <td><label for="time_entry_hours">Timer:</label></td>
    <td><%= f.text_field('hours', :size => 4, :value => entry.hours)
    <td><label for="time_entry_decription">Beskrivelse:</label></td>
    <td><%= f.text_field('description', :size => 40, :value =>
    <td id='submit'> <%= submit_tag 'Lagre' %></td>
<% end %>

On submit I receive: Parameters: {"time_entry"=>{"description"=>"Test",
"hours"=>"10"}, "commit"=>"Lagre", "period"=>"3", "action"=>"new",
"controller"=>"period"} as I expected but when changing the form_for to
form_remote_for I only receive this:

Parameters: {"period"=>"3", "action"=>"new", "controller"=>"period"}

Does anyone have a clue what I am missing here?

Thanks, Andrè