uncaught exception: controls.js requires including script.ac

hi friends...

Ajax problem....
please help me.
Ajax using delete the record

Browser Mozilla

my controller:

def delete
    Book.find(params[:id]).destroy
    redirect_to :action =>'book'
  end

my view:

<%= link_to_remote (image_tag("../images/delete_bt.gif", :border => 0)),
      :url =>{
           :controller=>"book",
           :action => 'delete',
           :id => s.id},
       :update=>"book#{s.id}",
       :loading=>"status('book#{s.id}')"
%>

Error....
uncaught exception: controls.js requires including script.aculo.us'
effects.js library

Line 0

Looks to me like you need to include the script.aculo.us library,
which is found in your public/javascripts/ folder. However, add this
to the <head> of your application layout:

<%= javascript_include_tag :defaults %>

Then make sure that everything is in the javascripts folder.

forgot it....
Thanks a lot friend..

Now working fine....