I don't know . But if the source you assigned in "src" inside the tag is a online one.
If you save go to that source and copy the script and save it in your local. Then
assign the "src" of your local one then it will work. ie.
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
<script type="text/javascript" src="../polin/jquery_library.js">
function fn()
{alert("pp");}
</script>
<script type="text/javascript">
$(document).ready(function(){
alert("ABC");
});
function fn()
{alert("oo");}
</script>
</script>
</head>
<body onload="fn()">
<p>THIS IS MY INDEX PAGE.</p>
</body>
</html>
src="../polin/jquery_library.js" this file is in my local where the jquery source script is saved. And it work