[Chartjs]-Chart.js tooltipTemplate not working

Here is an example of custom tooltip label:

var ctx = document.getElementById("myChart");

var barChartData = {
        labels : [ "Jan/16", "Feb/16", "Mar/16", "Abr/16", "May/16", "Jun/16", "Jul/16" ],
        datasets : [ {
            type : 'bar',
            label : "Revenue (US$)",
            data : [ 4000, 4850, 5900, 6210, 2500, 4000, 6500 ],
            backgroundColor : 'rgba(0, 0, 255, 0.3)'
        } ]
    };

var myChart = new Chart(ctx,
    {
        type : 'bar',
        data : barChartData,
        options : {
            responsive : true,
            tooltips : {

                callbacks : { // HERE YOU CUSTOMIZE THE LABELS
                    title : function() {
                        return '***** My custom label title *****';
                    },
                    beforeLabel : function(tooltipItem, data) {
                        return 'Month ' + ': ' + tooltipItem.xLabel;
                    },
                    label : function(tooltipItem, data) {
                        return data.datasets[tooltipItem.datasetIndex].label + ': ' + tooltipItem.yLabel;
                    },
                    afterLabel : function(tooltipItem, data) {
                        return '***** Test *****';
                    },
                }

            },
            scales : {
                xAxes : [ {
                    display : true,
                    labels : {
                        show : true,
                    }
                } ],
                yAxes : [ {
                    type : "linear",
                    display : true,
                    position : "left",
                    labels : { show : true },
                    ticks : {
                        beginAtZero : true
                    }
                } ]
            }
        }
    });