PHP Highcharts Graph If you select 1 day or the last day of each month, you can't see the graph.

Highcharts.setOptions({
            lang: {
                contextButtonTitle: "Printer Print",
                printChart: "Print Graph",
                downloadJPEG: "JPEG Download",
                downloadPDF: "PDF Download",
                downloadPNG: "PNG Download",
                downloadSVG: "Download SVG vector",
                Loading: "Loading..."
            }
        });
        Highcharts.chart('container', {
            chart: {
                type: 'column'
            },
            title: {
                text:picker+'Statistics by Media Graph'
            },
            xAxis: {
                type: 'datetime',
                labels: {
                    format: '{value:%d}'+'day',
                },
                pointInterval: 24 * 3600 * 1000, // one day
            },
            yAxis: {
                min: 0,
                title: {
                    text: ''
                },
                stackLabels: {
                    enabled: true,
                    style: {
                        fontWeight: 'bold',
                        color: (Highcharts.theme && Highcharts.theme.textColor) || 'gray'
                    }
                }
            },
            legend: {
                align: 'right',
                x: -30,
                verticalAlign: 'top',
                y: 25,
                floating: true,
                backgroundColor: (Highcharts.theme && Highcharts.theme.background2) || 'white',
                borderColor: '#CCC',
                borderWidth: 1,
                shadow: false
            },
            tooltip: {
                //headerFormat: '<b>{point.x}</b><br/>',
                pointFormat: '{series.name}: {point.y}<br/>Total: {point.stackTotal}'
            },
            plotOptions: {
                series: {
                    pointStart: Date.UTC(parseInt(picker_s[0].substring(0,4)), parseInt(picker_s[0].substring(5,7))-1, parseInt(picker_s[0].substring(8,10))),
                    pointInterval: 24 * 3600 * 1000 // one day
                },
                column: {
                    stacking: 'normal',
                    dataLabels: {
                        enabled: true,
                        color: (Highcharts.theme && Highcharts.theme.dataLabelsColor) || 'white'
                    }
                }
            },
            series: [{
                name: 'Introduction/Other',
                data: inflow_Data("h")
            }, {
                name: 'Home Page',
                data: inflow_Data("g")
            }, {
                name: 'Incall',
                data: inflow_Data("f")
            }, {
                name: 'Walking',
                data: inflow_Data("e")
            }, {
                name: 'Yellow ID',
                data: inflow_Data("c")
            }, {
                name: 'CPA',
                data: inflow_Data("b")
            }, {
                name: 'Landing/Keyword',
                data: inflow_Data("a")
            }, {
                type: 'spline',
                name: 'SNS',
                data: inflow_Data("d")
            }, {
                type: 'spline',
                name: 'Total',
                data: inflow_Data("i")
            }]
        });
    });