trouble in loading example czml file


I read the other posts about loading czml file and would like to try one out myself. I downloaded the simple.czml file from

Then I used the sample html code from other posts. (see below). When running this Simple_czml.html file on FireFox, I got the error :
[15:02:17.430] uncaught exception: DeveloperError: dataSourceCollection is required.

Please help.



if you use a Cesium Viewer instead of the Cesium Widget, it works right out of the box.


thank you for your reply. I still have problem. The page is blank. Console shows no warning or error, just one line showing the location of the html file.

Do I still use the widget.css and cesium.js? Below is the code. I am not sure how to paste the code with color.

Thank you.

Hello World! @import url(Cesium-full-b25/Build/Cesium//Widgets/widget.css);
  #cesiumContainer {
      position: absolute;
      top: 0;
      left: 0;
      height: 100%;
      width: 100%;
      margin: 0;
      overflow: hidden;
      padding: 0;
      font-family: sans-serif;

  body {
      padding: 0;
      margin: 0;
      overflow: hidden;
    var viewer = new Cesium.Viewer('cesiumContainer', {
        animation : false,
        baseLayerPicker : false,
        fullscreenButton : false,
        geocoder : false,
        homeButton : false,
        sceneModePicker : false,
        timeline : false,
        infoBox : false,
        //Use standard Cesium terrain
        terrainProvider : new Cesium.CesiumTerrainProvider({
            url : '',
            credit : 'Terrain data courtesy Analytical Graphics, Inc.'

    //Allow users to zoom and follow objects loaded from CZML by clicking on it.

    var czmlSource = new Cesium.CzmlDataSource();


Found my own mistake. I am missing before the .