Coach_May:
Where I was brought up, this was called "common courtesy". When somebody reaches out to you, there's a moral obligation to reply.
It's no different if that person is asking for help or offering help, you should do your part to supply the appropriate response. It might be "thanks", it might be, "I'll be there as soon as I can".
Kids today need to live through some hard times to understand this perspective. Even though we're in tough economic times right now, it hasn't resonated with the younger generation just yet and they all seem to be asking, "what's in this for me", instead of "what can I do for us".
But I digress