Morris line chart Empty - morris.js

Question

I have this weird problem at displaying Morris line chart.
It only displays data when I let the revenue-chart at the same page.
When I erase the block of revenue-chart, the line chart gets empty.
These are the codes before and after:
Functional:
<section class="content">
<div class="row">
<div class="col-md-6">
<div class="box box-primary">
<div class="box-header with-border">
<h3 class="box-title">Area Chart</h3>
<div class="box-tools pull-right">
<button type="button" class="btn btn-box-tool" data-widget="collapse"><i class="fa fa-minus"></i>
</button>
<button type="button" class="btn btn-box-tool" data-widget="remove"><i class="fa fa-times"></i></button>
</div>
</div>
<div class="box-body chart-responsive">
<div class="chart" id="revenue-chart" style="height: 300px;"></div>
</div>
</div>
</div>
<div class="col-md-6">
<div class="box box-primary">
<div class="box-header with-border">
<h3 class="box-title">Line Chart</h3>
<div class="box-tools pull-right">
<button type="button" class="btn btn-box-tool" data-widget="collapse"><i class="fa fa-minus"></i>
</button>
<button type="button" class="btn btn-box-tool" data-widget="remove"><i class="fa fa-times"></i></button>
</div>
</div>
<div class="box-body chart-responsive">
<div class="chart" id="line-chart" style="height: 300px;"></div>
</div>
</div>
</div>
</div>
</section>
Error:
<section class="content">
<div class="row">
<div class="col-md-6">
<div class="box box-primary">
<div class="box-header with-border">
<h3 class="box-title">Line Chart</h3>
<div class="box-tools pull-right">
<button type="button" class="btn btn-box-tool" data-widget="collapse"><i class="fa fa-minus"></i>
</button>
<button type="button" class="btn btn-box-tool" data-widget="remove"><i class="fa fa-times"></i></button>
</div>
</div>
<div class="box-body chart-responsive">
<div class="chart" id="line-chart" style="height: 300px;"></div>
</div>
</div>
</div>
</div>
</section>

Answer 1

I have found the problem.
But it was not logical.
I deleted the javascript code block for the revenue-chart:
// AREA CHART
var area = new Morris.Area({
element: 'revenue-chart',
resize: true,
data: [
{y: '2011 Q1', item1: 2666, item2: 2666},
{y: '2011 Q2', item1: 2778, item2: 2294},
{y: '2011 Q3', item1: 4912, item2: 1969},
{y: '2011 Q4', item1: 3767, item2: 3597},
{y: '2012 Q1', item1: 6810, item2: 1914},
{y: '2012 Q2', item1: 5670, item2: 4293},
{y: '2012 Q3', item1: 4820, item2: 3795},
{y: '2012 Q4', item1: 15073, item2: 5967},
{y: '2013 Q1', item1: 10687, item2: 4460},
{y: '2013 Q2', item1: 8432, item2: 5713}
],
xkey: 'y',
ykeys: ['item1', 'item2'],
labels: ['Item 1', 'Item 2'],
lineColors: ['#a0d0e0', '#3c8dbc'],
hideHover: 'auto'
});
At some way it was conflicting with the line-chart.
// LINE CHART
var line = new Morris.Line({
element: 'line-chart',
resize: true,
data: [
{y: '2011 Q1', item1: 2666},
{y: '2011 Q2', item1: 2778},
{y: '2011 Q3', item1: 4912},
{y: '2011 Q4', item1: 3767},
{y: '2012 Q1', item1: 6810},
{y: '2012 Q2', item1: 5670},
{y: '2012 Q3', item1: 4820},
{y: '2012 Q4', item1: 15073},
{y: '2013 Q1', item1: 10687},
{y: '2013 Q2', item1: 8432}
],
xkey: 'y',
ykeys: ['item1'],
labels: ['Item 1'],
lineColors: ['#3c8dbc'],
hideHover: 'auto'
});