Displaying the map after a button click event

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C#

ASP.NET

Google-Maps

hello
I have a problem with displaying maps
in page load the map is displayed, but when I want to execute the code on a button click the map is not displayed

function javascript to display Map

 function AfficherMap() {
//     alert("ssss");
        var mapOptions = {
            center: new google.maps.LatLng(markers[0].lat, markers[0].lng),
            zoom: 10,
            mapTypeId: google.maps.MapTypeId.ROADMAP
        };
        var map = new google.maps.Map(document.getElementById("map-canvas"), mapOptions);
        var infoWindow = new google.maps.InfoWindow();
        var lat_lng = new Array();
        var latlngbounds = new google.maps.LatLngBounds();
        for (i = 0; i < markers.length; i++) {
            var data = markers[i]
            var myLatlng = new google.maps.LatLng(data.lat, data.lng);
            lat_lng.push(myLatlng);
           
            var marker = new google.maps.Marker({
                position: myLatlng,
                map: map,
                title: data.title
            });
            latlngbounds.extend(marker.position);
            (function (marker, data) {
                google.maps.event.addListener(marker, "click", function (e) {
                    infoWindow.setContent(data.description);
                    infoWindow.open(map, marker);
                });
            })(marker, data);
        }
        map.setCenter(latlngbounds.getCenter());
        map.fitBounds(latlngbounds);
        /////////////////////////////////////////77777

        var service = new google.maps.DirectionsService();
        var directionsDisplay = new google.maps.DirectionsRenderer();    
        directionsDisplay.setMap(map);

var waypts = [];
for(j=1;j<lat_lng.length-1;j++){            
      waypts.push({location: lat_lng[j],
                   stopover: true});
}

var request = {
    origin: lat_lng[0],
    destination: lat_lng[lat_lng.length-1],
    waypoints: waypts,
    travelMode: google.maps.DirectionsTravelMode.DRIVING
  };
        service.route(request,function(result, status) {                
            if(status == google.maps.DirectionsStatus.OK) {                 
                  directionsDisplay.setDirections(result);
            } else { alert("Directions request failed:" +status); }
        });
    }

Button Click

protected void Button3_Click(object sender, EventArgs e)
      {

          string s = "2014-11-05";
          LocalisationVenteDao.ds.Reset();
          LocalisationVenteDao.Instance.LocalisationVenteToDB(Sql.Instance.GetSqlConnection(),s);
          rptMarkers.DataSource = LocalisationVenteDao.ds.Tables[0];
          GridView1.DataSource = LocalisationVenteDao.ds.Tables[0];
          rptMarkers.DataBind();
          GridView1.DataBind();
          ClientScript.RegisterStartupScript(this.GetType(), "blablaosef", "<script type='text/javascript'>AfficherMap();</script>");


      }