Autocomplete error please help

I need to implement auto complete in my form.
I have installed autocaomplete for rails 2.0
in the

person form i have
<%form_for(:person,:url=>{:action =>"submit_tag"} do p %>
First Name:<%= text_field_with_auto_complete p, "first_name" %>

in the person controller i have

auto_complete_for :person, :first_name

also in the application layout i have
<%= javascript_include_tag :defaults %>

Now when i try to open the page the autocomplete does not work and i get
the following:

line: 667
char: 1
Error : Object expected
code: 0

Please tell me what is going wrong
Thank you.