为什么我不能在JSON中使用2个格式化程序函数？

Question

首先我有这个功能：

 "formatter" : function () {
        var s = "";
                    var sum  = 0;
                    var bugType = 0;
                    var color = '';
                    var date = new Date(this.points[0].x);
                    for (var i = 0; i < this.points.length; ++i) {
                       if (this.points[i].series.visible) {
                            bugType = this.points[i].series.name;
                            color = this.points[i].series.color;
                            s += '<span style="color:'+color+';">'+bugType+'</span>' + " = "+ this.points[i].y+'<br>';
                            sum += this.points[i].y;
                       }
                    }
                     s = date.toDateString() + "<br>" + '<span style="color:#FF3333;">Total values</span>'+' = ' +sum +'<br>' +s;
                   return s;
    },

然后这个：

"pointFormat":
    "<span style=\"color:{series.color}\">{series.name}</span>:
         <b>{point.percentage:.1f}%</b>
         ({point.y:,.0f} bugs)<br/>"

为什么第二点格式无法识别/不起作用？

谢谢！

按要求完成查询：

{
    "chart": {
        "type": "area"
    },
    "plotOptions": {
        "series": {
            "marker": {
                "enabled": false
            },
            "stacking": "percent"
        },
        "area": {
            "stacking": "percent"
        }
    },
    "yAxis": {
        "max": 60,
        "title": {
            "text": "Percentage"
        }
    },
    "tooltip": {
        "shared": true,
        "formatter": function () {
            var s = "";
            var sum = 0;


            var date = new Date(this.points[0].x);
            for (var i = 0; i < this.points.length; ++i) {
                if (this.points[i].series.visible) {

                    color = this.points[i].series.color;
                    s += '<span style="color:' + color + ';">' + bugType + '</span>' + " = " + this.points[i].y + '<br>';
                    sum += this.points[i].y;
                }
            }
            s = date.toDateString() + "<br>" + '<span style="color:#FF3399;">Total values</span>' + ' = ' + sum + '<br>' + s;
            return s;
        },
        "valuePrefix": null,
        "valueSuffix": "%",
        "pointFormat": "<span style=\"color:{series.color}\">{series.name}</span>: <b>{point.percentage:.1f}%</b> ({point.y:,.0f} bugs)<br/>"
    },

    "subtitle": {
        "text": "Subtitle"
    },
    "title": {
        "text": "Title"
    },

    "xAxis": {
        "type": "datetime"
    },