[jQuery] jQuery dollar not defined

I can not find why $ (dollar) is not defined in my code.
This is the include-part:
    <style type="text/css" media="all">
    @import "http://jquery.com/demo/thickbox/css/global.css";
    @import "http://jquery.com/demo/thickbox/thickbox-code/thickbox.css";
    </style>
    <link rel="alternate stylesheet" type="text/css" href="http://
jquery.com/demo/thickbox/css/1024.css" title="1024 x 768" />
    <script src="http://jquery.com/demo/thickbox/js/
jquery-1.1.3.1.pack.js" type="text/javascript"></script>
    <script src="http://jquery.com/demo/thickbox/thickbox-code/thickbox-
compressed.js" type="text/javascript"></script>
    <script src="http://jquery.com/demo/thickbox/js/global.js" type="text/
javascript"></script>
Still the same error.
I want to call a jquery-thickbox.
Anybody?