yAxis lable issue with no data

by Anil D

HTML

<script src="http://code.highcharts.com/stock/highstock.js"></script>
<div id="container" style="width:810px;height: 400px; margin: 0 auto"></div>

JavaScript

function makeData(obj, length, cols, max) {
	var myd = new Date('2015/04/22 10:00');
	var mm = Math.floor(myd.getMinutes() / 10) * 10;
	myd.setMinutes(mm);
	myd.setSeconds(0);
	myd.setMilliseconds(0);

	for (i = 0; i < length; i++) {
		addMin = i * 10 * 60 * 1000;
		var colArray = [ myd.getTime() + addMin ];
		for (k = 0; k < cols; k++) {
			colArray.push(Math.round(Math.random() * max));
		}
		obj.push(colArray);
	}
};

function makeStackedData(data) {
	var dataArray = [];
	var dataLength = data.length;
	var dataCols = data[0].length;

	for (var k = 1; k < dataCols; k++) {
		var stackArray = [];
		for (var i = 0; i < dataLength; i++) {
			if (k == 1) {
				stackArray.push([ data[i][0], data[i][k], data[i][k], 0, 0 ]);
			} else {
				var startValue = dataArray[k - 2][i][2];
				stackArray.push([ data[i][0], startValue + data[i][k],
						startValue + data[i][k], startValue, startValue ]);
			}
		}
		dataArray.push(stackArray);
	}
	return dataArray;
};

	$(function() {
		
		var graphData = [];
		var dummy_max = 50;

		var chart_width = dummy_max * 70;
		var dateAndTimeArray = [];

		makeData(graphData, dummy_max, 4, 200);
		graphData = makeStackedData(graphData);
		var dateAndTimeArray = [];
		var time = 1429677000000;
		dateAndTimeArray.push(time);
		for(idx=0; idx<50 ; idx++){
			time+=600000;
			dateAndTimeArray.push(time);
		}
                   for(var i in graphData[0]){
                	  if(i < 30){
                		  graphData[0][i][1]=0;
                	  }
                  }
		$('#container')
				.highcharts(
						{
							plotOptions : {
								series : {
									stacking : 'normal',
					                pointStart: 1429688400000,
					                pointInterval:  60 * 1000

								},
								pointWidth	: 20,
								groupPadding: 0,
							},

							chart : {
					            plotBackgroundColor: "rgba(255, 255, 255, 0.4)",
					            backgroundColor: "#0072FF",
								type : 'column',
								height : 400,
								width :...