Google Map API not working

Google Map API not working

What is wrong with my code below?

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title>Maps</title>
    <script type="text/javascript" src="http://maps.googleapis.com/maps/api/js?sensor=false"></script>
    <script type="text/javascript" src="jquery-1.9.0.min.js"></script>
     <script type="text/javascript">
    var map;

    function initialize() {

        alert('Hi');

        var myOptions={
            zoom: 14,
            center: new google.maps.LatLng(22.451649,88.461914),
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };

        var mapDiv = $('#map_Div').get(0);
        map = new google.maps.Map(mapDiv,myOptions);
    }

    google.maps.event.addDomListener(window, 'load', initialize);
</script>



</head>
<body>
<div id="grid">
    <div id="map_Div"></div>
</div>
</body>
</html>