I have a question about the film 'Chitty Chitty Bang Bang'?

Okay, so this is a really daft question but i'm a little bit confused? When the child catcher is talking about how ice cream and lolly pops etc, are all free today, he looks through the window that the two children are in, he looks right at them and there making eye contact, but then the child catcher just skips away and doesn't bother to come down and get them, why is this? Why does he walk away instead of getting the children?