Highcharts showLoading at the beginning

Question

I am trying to show the loading text or an animation when my page opens, but somehow it doesn't work and I am not getting wiser from this explanation: http://api.highcharts.com/highstock/Chart.showLoading I have also checked various examples with a button, but unfortunately it also did not work for me. This is a snippet from my code:

<script>
            $(function () {
                chart.showLoading('Loading data ...');
                $.getJSON('http://url/data_1/', function (data) {

                    // define and process data
                    var ohlc = [] ;
                    ohlc.push([...]);
                    ...
                    }

                    // create the chart
                    var chart = Highcharts.stockChart('container', {
                        plotOptions: { ... },
                        series: [{ ... }],
                        });
                    });
</script>

I very much appreciate any help.