series.remove() problem

by jlbriggs

HTML

<script src="http://code.highcharts.com/highcharts.js"></script>
<script src="http://code.highcharts.com/highcharts-more.js"></script>
<script src="http://code.highcharts.com/modules/exporting.js"></script>

<form id="data-menu">
    <label for="data-select" class="radio">Select Data:</label>
    <select id="data-select" autocomplete="off">
        <option selected="selected" value="sdb">Sales $ Billed</option>
        <option  value="sdo">Sales $ Ordered</option>
        <option  value="pdb">PO $ Billed</option>
        <option  value="pdo">PO $ Ordered</option>
    </select>
</form>
	
<div id="billed" style="height:200px;margin:1.5em 1em;"></div>

JavaScript

var billed;
$(function() {
    
    $('#data-menu').submit(function(e) {
        e.preventDefault();
    });
    $('#data-select').change(function(e) {
        var set = $(this).val();
        updateData(billed,set);
    });
    
    var options = {
        chart: {
            margin:[5,175,25,60]
        },
        title: { text: '' },
        legend: { 
            layout: 'vertical',
            align:'right',
            verticalAlign:'middle',
            itemWidth:135
        },
        tooltip: {
            useHTML:true,
            crosshairs: true,
            shared: true,
            style: {
                padding:'2px'
            },
            formatter: function() {
                var points='<table class="tip"><caption>'+Highcharts.dateFormat('%B',this.x)+'</caption><tbody>';
                $.each(this.points,function(i,point) {
                    points 	+='<tr><th style="background-color: '+point.series.color+'!important;border:1px solid #fff!important;">&nbsp;&nbsp;</th>'
                    + '<th style="text-align: left">'+ point.series.name +': </th>'
                    + '<td style="text-align: right"> '+Highcharts.numberFormat(point.y,2)+'</td></tr>'
                });
                if(typeof(this.points[0]) != 'undefined' && typeof(this.points[1]) != 'undefined') {
                    points 	+='<tr><th style="background-color:#eee!important;border:1px solid #fff!important;">&nbsp;&nbsp;</th>'
                    + '<th style="text-align: left">Difference: </th>'
                    + '<td style="text-align: right"> '+Highcharts.numberFormat(this.points[0].y - this.points[1].y,2)+'</td></tr>'
                    + '</tbody></table>';
                }
                return points;
            }    
        },
        plotOptions: {
            series: {
                shadow: {
                    color:'rgba(255,255,255,1)',
                    offsetX:0,
                    offsetY:0,
                    opacity:1,
        ...