Doughnut chart using angular-chart

Question

I am trying to use angular charts and began with doughnut chart. I added the following code in javascript.

$scope.labels = ["Download Sales", "In-Store Sales", "Mail-Order Sales"];

$scope.data = [300, 500, 100];

$scope.color= ['#90EE90', '#FF6600', '#8080FF'];

And the following code in HTML

<canvas id="doughnut" class="chart chart-doughnut" chart-data="data" chart-colors="color" chart-labels="labels">
    </canvas>

But in my HTML nothing is displayed. I can see div with "chart-container" class in the HTML markup in the DOM but nothing is displayed in the page. I have added the chart.js and angular-chart.js scripts in the html and added the dependency chart.js in my module. Any help in this regards will be highly appreciated.