Let me say I am still fairly new to google maps and javascript. i\'ve been mixing together the google store locator tutorial with some other stuff. So far, I am using mark
you've got infowindow.open(map,marker); but I don't see where you create marker (apart from the local variable in your createMarkers function, which you can't really access at this point). Shouldn't that be infowindow.open(map,markerCluster);
Another suggestion. The second parameter is where the infowindow gets anchored to. However, you don't need it. When you create your infowindow, you can set a position property (i.e. use the same lat/lng as the marker has). Then you can just call infowindow.open(map);