RSVP?

Okay, time for a complaining blog...
Why don't people ever RSVP? Especially if it says, "RSVP" right on the invitation?
I am very frustrated right now because Samantha invited 4 little girls to her party in two days and I haven't heard so much as "Boo!" from any of them. How am I supposed to know if they're coming? How do I know I won't have a crying child in 2 days? So, now I'm stuck trying to call these people to see if they're coming. There is a problem here though. We are new to the Ward and I don't know these girls' parents very well yet, and I have nobody's phone number! Luckily, I DO have the phone number of the Activities Days leader, so I have a call in to her to get the girls' number. But will she return my call? ACK!!!
So here is my plea to all of you out there, Please always, always respond to an RSVP. You will be saving the host such a HUGE headache!