$().resizeable is not a function

$().resizeable is not a function

i have the following which works fine in production but not in my dev.
 
        #output
        {
            width: 50%;
            height: 100%;
            position: absolute;
            left: 50%;
            top: 0;
            border: 1px solid rgb(190,190,190);
        }







 
    <script type="text/javascript" src=" http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
    <script src="/js/JQUERY/js/jquery-ui-1.7.2.custom.min.js" type="text/javascript"></script>
    <script src="/js/codemirror/js/codemirror.js" type="text/javascript"></script>

 
this is the line causing an issue.
$( "#output" ).resizable( "option" , "maxWidth" , $( '#body' ).width() - 260);
 
Dev Environment:
Win XP (WIN 2003 IN PRODUCTION)
ASP.NET 2.0
AJAX 1.0
 
Am i missing any include or it is a problem of other declaration
 
Any thoughts?
 
Thanks