change colour problem; trivial, I'm sure - but I can't figure it out

[rippon]

I simply want to draw two line segments, the first in blue, the second in red:

function testDraw(){
	context.moveTo(0,0); context.lineTo(myCanvasWidth/2, myCanvasHeight/2);
	context.strokeStyle = "blue";
	context.stroke();
	context.lineTo(myCanvasWidth, 0);
	context.strokeStyle = "red";
	context.stroke();
}

The problem is that the first blue line segment is gone over again - in red.

I'm a javascript beginner, and I'm sure this is trivial, but I'd appreciate help nevertheless.
Thanks.