使用javascript更改iframe中的链接

I am trying to change iframe link using java script but script is not working.

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <title></title>
    <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">

</head>
<body>
    <iframe name="pageChange" src="about:blank" width="1300" height="1300" scrolling="auto" frameborder="1" onload=pageChange></iframe>
    <script type="text/javascript">
        var pages=new Array();
        pages[0]="http://valuewingcoe.com";
        pages[1]="http://www.link2.com";
        pages[2]="http://www.link3.com";
        pages[3]="http://www.link4.com";
        var time=7000; // this is set in milliseconds
        function pageChange() {
            var rand=Math.floor(Math.random()*pages.length);
            document.getElementById("frame").src=pages[rand];
            setTimeout("pageChange()",time);
        }
        onload=pageChange;
    </script>
</body>
</html>

You don't have any HTML element with "frame" as ID. Also wrong declaration for the onload attribute.

<iframe id="frame" name="pageChange" src="about:blank" width="1300" height="1300" scrolling="auto" frameborder="1" onload="pageChange()"></iframe>