Visual Studio 2010 - JQuery Rounded Corners - Error

Visual Studio 2010 - JQuery Rounded Corners - Error

Hi All.
 
I'm tearing my hair out trying to work out why I can't get JQuery Rounded Corners working when attempting to implement within Visual Studio 2010.
 
I have the following defined in the Site.Master:
 

  1. <script src="Scripts/jquery-1.4.1.min.js" language ="javascript" type="text/javascript" />

    <script src="Scripts/jquery.colorbox-min.js" language ="javascript" type="text/javascript" />

    <script src="Scripts/jquery.ui.js" language ="javascript" type="text/javascript" />

    <script src="Scripts/jquery.corners.min.js" language ="javascript" type="text/javascript" />

    <script type="text/javascript"></script>

 
On my page (Default.aspx), I have the following:
 

  1. <script type="text/javascript">

    $(document).ready(

    function () {

    // add code here

    //$('#rcorners').corners();

    $(

    '.box').corners('20px');

    });

    </script>

When I attempt to run the site (F5), I am prompted with the following error:
 
Microsoft jscript runtime error: object doesn't support this property or method.
 
The line being highlighted is: $('.box').corners('20');
 
Has anyone successfully implemented JQuery Rounded Corners within Visual Studio 2010?
 
Ben