Highcharts draggable points in line type gets hidden with axis

Question

I am little bit confused with Hightcharts draggable points where the points are getting hidden over the axis in iPad (touch device)

I am using "draggable-points" plugin to drag over with Hightcharts.

If anybody faced this kind of a problem, please answer me.

Thanks in advance.

this.chartBoard = new Highcharts.Chart({

    title: {
        text: 'Line graph'
    },
    chart: {
        renderTo: graphContainer,
        animation: false,
        backgroundColor: 'rgba(255, 255, 255, 0.1)',
        width : 700,
       height : 330
    }
    xAxis: {
        categories: categoriesArray,
           lineColor: '#000',
           lineWidth: 2,
           tickmarkPlacement: 'on',
           gridLineWidth: 1,
           gridLineColor: '#F2F2F2'
    },
    yAxis: {
        min: minY,
        max: maxY,
        tickInterval: scaleY,
        minorTickLength: 2,
        lineColor: '#000',
        lineWidth: 2
    },
    series: [{
        id : "series",
        data: categoriesValueArray,
        draggableY: true,
        dragMinY: minY,
        dragMaxY: maxY,
        type: chartType,
        minPointLength: snapsPerLine,
        color: "#95B9EC",
        marker: {
            radius: pointRadius
        }
     }]
});