Auto_complete

Hi guys,
I have install auto_complete from here

then
#my controller is
auto_complete_for :post, :title
protect_from_forgery :only => [:create, :delete, :update]
#My view
<%= text_field_with_auto_complete :post, :title %>
But when I type in title field then there is not happened and there is
nothing error recorded in error console of firefox.
Any suggestion? I have googled a lot every. where there is the same
solution.

I am using rails 2.2.2.
is it a problem?
Please show a way
Thanks in advance.

Tuhin