jQuery plugin for AutoComplete not working

Question

I have the following code in my ASPX page:

<script src="../Scripts/jquery-1.4.1.js" type="text/javascript"></script>
<script src="../Scripts/jquery.autocomplete.js" type="text/javascript"></script>
<script src="../Scripts/localdata.js" type="text/javascript"></script>
<script type="text/javascript">
    $().ready(function () {

        $('#<%=txtEmail.ClientID%>').autocomplete(emailExtensions, {
            multiple: true,
            mustMatch: true,
            autoFill: true
        });
    });

*-Required

But my jQuery gives error saying the value is null. What am I doing wrong?