Like I said, its all about truthfulness and integrity....not candy machines! Looks like "You're all shook up"...sing it Elvis!
There is a reaction that children have called "shaking the candy machine". I might be making the term up so bear with me.
Whenever you try to stop a particular behavior in a child by ignoring it inevitably the first reaction is an increase in that behavior. If it is screaming, the screaming at first becomes louder and more frequent.
This reaction is like someone who put their money in a candy machine and the candy did not come out. They shake the machine a little and get no satisfaction. Then they continue to shake the machine harder and harder until one of two things happened, they either get the candy or they give up and walk away.
It just takes a little resolve to resist giving in to the increased screaming at first. But eventually if you stick with it, the behavior stops.