Drawing a basic shape from within Amber

Hi group,

I'm trying to draw a simple rectangle from within Amber, but haven't succeeded so far. 

This is what I do:

          MyWidget>>renderOn: html

          canvas := html canvas.

         canvas 

         id: 'drawingBoard';

         width: '400';

         height: '400'. 

         graphicsContext := (document getElementById: 'drawingBoard')  getContext: '2d'.

         graphicsContext strokeRect: #(25 25 100 100).

Any ideas what I'm doing wrong?

Regards,

RD