Googlemaps api MarkerClusterer problem

Ajax is asynchronous. What happened, you created MarkerClusterer before the callback function ended, and thus the marker was not placed in the markersArray global array. It's just on my head without any testing, but see if it solves the problem.

var markersArray = [], markerCluster;

function getMarkers(hours) {//5

    if (markersArray) {
        for (i in markersArray) {
            markersArray[i].setMap(null);
        }
        markersArray.length = 0;
    }

    image = '/images/site/tw.png';

    $.ajax({
        url: "updateMarkers",
        type:"POST",
        data:{"hours": hours},
        success: function(data){
            data = $.parseJSON( data );
            if (data.Locations.length>0) {//2
                    for (i=0; i<data.Locations.length; i++) {//1
                        loc = new google.maps.LatLng(data.Locations[i].lat, data.Locations[i].lng);

                        marker = new google.maps.Marker({
                            position: loc,
                            map: map,
                            icon: image,
                            html: content
                        });

                        markersArray.push(marker);

                        infowindow = new google.maps.InfoWindow({
                            content: "holding..."
                        });

                        google.maps.event.addListener(marker, 'click', function() {
                            infowindow.open(map, this);
                            infowindow.setContent(this.html);
                        });
                    }//1

                    //Create the Cluster AFTER all markers are pushed into the markersArray, and make sure it called within the callback function
                    markerCluster = new MarkerClusterer(map, markersArray);
                }//2
            }
        });

}//5

getMarkers(24);