How do you get a 6mo to start using a spouted cup?? Tried to give her some water from one this afternoon and she just held it in her mouth. If I leave the valve in she doesn't know to suck, if I take the valve out she just has a mouth full of water that she lets dribble out of her mouth?? She started taking little mouthfuls of water from a doidy cup, shall I just stick with that?