How to use jQuery autocomplete correctly?

I am trying to use autocomplete from

http://dev.jquery.com/view/trunk/plugins/autocomplete/jquery.autocomplete.js

but am getting this error. textbox is the id of the input field where autocomplete should happen:

I have tried to foll开发者_运维问答ow the example given on this page. What am I doing wrong here?

Getting the same error on using ready:

I think, you have NOT included the script yet. Put this in the head of your page and test.

<script  src="http://dev.jquery.com/view/trunk/plugins/autocomplete/jquery.autocomplete.js"/>

include jquery.js and autocomplete.js on the top of page and write the code inside

$(document).ready(function(){
// right here
});