background image watchFace

Dear Community,

Question:

How to set background png image?

What I've tried:

in onUpdate method:

        var toDraw = WatchUi.loadResource(Rez.Drawables.background);
        dc.drawBitmap(0,0,toDraw);

created: resources/drawables/background.xml and places png image (240x240) background.png in same drawables folder.

<drawables>
<bitmap id="background" filename="background.png"/>
</drawables>
There is no build error as well as no background image.
Other methods I tried, didn't even compile.
Api lvl:3.3.0
Regards,