I'm very sorry you didn't get any kind of acknowledgement.
How old are your kids? Do they generally observe traditions? Do you have a good relationship with them?
This might not be a good idea, but I'm going to throw it out there. Maybe wait a week or two, and then ask them why they didn't send anything. Maybe you need to tell them you'd appreciate a card & a phone call.
If there is another problem, perhaps you can work it out with them. Hugs!