Unable to drag bpmn elements to canvas

Hi Everyone, I have taken code from following URL and trying to modify the example as per my requirements.

In the above example, I see that a bpmn file (diagramUrl) been downloaded using http service and loaded on startup. But when I comment the “loadUrl()” from diagram.component.ts I see that application is opening with no elements added but I am unable to drag n drop an element from pallette to canvas.
For making the canvas droppable, Is it mandatory to load any bpmn file on startup. Please clarify.

bpmn-js itself doesn’t include drag and drop functionality. The angular example doesn’t include it either. As you can in the demo you can easily build it on top.