search form error

[Suec]

Hi,

Just started with searchlogic, and bumped into a strange error. I got
error when I code:
<% form_for @search do |f| %>,

but it is fine:
<% form_tag articles_path, :method => 'get' do %>
<%= text_field_tag :search, params[:search],

error:
Called id for nil, which would mistakenly be 4 -- if you really wanted
the id of nil, use object_id

trace:
/usr/local/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/
action_controller/record_identifier.rb:76:in `dom_id'
/usr/local/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/
action_view/helpers/record_identification_helper.rb:16:in `dom_id'
/usr/local/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/
action_view/helpers/form_helper.rb:293:in `apply_form_for_options!'
/usr/local/ruby/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/
action_view/helpers/form_helper.rb:277:in `form_for'
........................

Anyone, can shed some light on this?

Thanks,
Sue