having problems doing my first example on jQuery

having problems doing my first example on jQuery

Hi i am kash

I have started learning how to use jQuery. i have been using the book jQuery for dummies. But
i have encounted my first problem doing the first exercise.
This is the code i used:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
           "http://www.w3.org/TR/xhtm11/DTD/xhtm11-strict.dtd">
<html>

<head>
<title>My Test Page</title>
<script type="text/javascript" src="js/jquery-1.11.0.js"></script>
<script type="text/javascript">
$(document).ready(function(){
    alert(jQuery('img').attr('alt'));
});
</script>
   
</head>
<body>
This is my test page.
<img src= "images/home.gif" height="28" width="28" alt="This is a test image.">

</body>
</html>

but the popup alert box does not appear.

please help
thanx