loadGraphic(AssetPaths.player__png, true, 16, 16);
setFacingFlip(FlxObject.LEFT, false, false);
setFacingFlip(FlxObject.RIGHT, true, false);
animation.add("d", [0, 1, 0, 2], 6, true);
Can you post the image you're using? It sounds like there's a problem with how you locate the frames of your sprite sheet.
If you make it a 48x16 strip with each frame being 16x16, it should work. Like so:
Or, if you make the image 32x32 like this it should work too
where frame 3 is a blank area.
If you have a blank area in your image it will show nothing for that frame of the animation and blink.
So, in this case frame 2 is a blank area and will show nothing when animation frame 2 is drawn.