Cannot read property 'addGraph' of undefined in meteorJS - nvd3 - mongodb

Question

Using the official nvd3 package (https://atmospherejs.com/nvd3/nvd3)
I have the following code under the Template.rendered block:
var formattedEarnedData = formatEarnedData(userEarnedDataSet);
nv.addGraph(function() {
var earnedChart = nv.models.lineChart()
.margin({ left: 25 })
.useInteractiveGuideline(true)
.transition()
.duration(350)
.showLegend(true)
.showYAxis(true)
.showXAxis(true);
earnedChart.xAxis
.axisLabel('Date')
.tickFormat(d3.format('d'));
earnedChart.yAxis
.axisLabel('Earned')
.tickFormat(d3.format('d'));
d3.select('#earned-charts svg').datum(
[{
key: 'Earned',
values: formattedEarnedData
}]
).call(earnedChart);
nv.utils.windowResize(earnedChart.update);
return earnedChart;
});
The following lies at the bottom of the js file outside of the rendered block:
var formatEarnedData = function(dataSet) {
var earnedDataArray = new Array();
var groupedDates = _.groupBy(_.pluck(dataSet, 'progression'), function(date) {
return moment(date).format('MMM D');
});
_.each(_.values(groupedDates), function(dates) {
earnedDataArray.push({
date: dates[0],
total: dates.length
});
});
return earnedDataArray;
}
Even after following the documentation, I am still getting this error:
Cannot read property 'addGraph' of undefined
Can any nvd3 experts shed some light on why this error is happening?
Thanks in advance.