Textbox with Autocomplete

Question

I want to make a textbox show me the names of registered users in the bank while I type. Ex: if I type the letter r, the textbox should show me some options that contain the letter r, but, I’m not getting it to work. Did I forget something?

Here’s the code I’m using:

<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/cupertino/jquery-ui.css" type="text/css" rel="Stylesheet" />
    <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4/jquery.min.js" type="text/javascript"></script>
    <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js" type="text/javascript"></script>
    <script type="text/javascript">
            $(document).ready(function () {
                $("#txtPesq").autocomplete({
                    source: '@Url.Action("pesquisarUsuario")',
                    minLength: 0
                });
            });
    </script>






<h2>Index</h2>


@using (@Html.BeginForm())
{
    @Html.TextBox("pesquisa", null, new { id = "txtPesq" })
    <input type="submit" value="Pesquisar" />



}