Hi Camila

Bit of a vague question, but I think I know what you're doing based on your previous posts. If your still following the flow-free tutorial, I think you want to just change the color property of the line SceneObject, since the sprite is looking at that property to determine what to draw. Once again, remember to call setDirtyArea to tell WADE to redraw the line:

lineObject.color = 'red';lineObject.getSprite().setDirtyArea();

If I'm misunderstanding what you want to do, please post some code of what you are doing at the moment to draw those lines and I'll look at it.