图例设置了却不显示

var option = {
    title: {
        text: '医疗全成本收益',
        subtext: '',
        x: 'left'
    },
    tooltip: {
        trigger: 'axis',
        axisPointer: {            // 坐标轴指示器，坐标轴触发有效
            type: 'shadow'        // 默认为直线，可选为：'line' | 'shadow'
        }
    },
    legend: {
        data: ['医疗收入', '医疗全成本', '医疗全成本收益'],
        y: 'bottom',
        x: 'center'
    },
    toolbox: {
        show: true,
        feature: {
            mark: {show: true},
            dataView: {show: true, readOnly: false},
            magicType: {show: true, type: ['line', 'bar', 'stack', 'tiled']},
            restore: {show: true},
            saveAsImage: {show: true}
        }
    },
    calculable: true,
    xAxis: [
        {
            type: 'category',
            data: []
            //data:[]
        }
    ],
    yAxis: [
        {
            type: 'value',
            axisLabel: {
                formatter: function (value) {
                    return value / (10000 * 10000 ) + "亿";
                }
            }
        },
        {
            type: 'value',
            axisLabel: {
                formatter: function (value) {
                    return value / (10000 * 10000 ) + "亿";
                }
            }
        }
    ],
    series: [
        {
            name: '医疗收入',
            type: 'line',
            stack: '总量',
            barWidth: 20,
            itemStyle: {normal: {label: {show: true, position: 'insideRight'}}},
            data: []
            //data:[]
        },
        {
            name: '医疗全成本',//这个是对应的图例，动态添加输出的话必须与这个名字对应，如果不一致该图例隐藏，但chart效果不隐藏
            type: 'line',
            stack: '总量',
            barWidth: 20,
            itemStyle: {normal: {label: {show: true, position: 'insideRight'}}},
            data: []
            //data:[]
        },
        {
            name: '医疗全成本收益',
            type: 'line',
            stack: '总量', yAxisIndex: 1,
            itemStyle: {normal: {label: {show: true, position: 'insideRight'}}},
            data: []
            //data:[]
        }

    ]
};