Give it a few days and you will get a thankyou im sure. The average kid must have got 20+ presents yesterday so it is a bit much to expect them to show full gratitude so soon to all kind and generous donors! (although, not unreasonable of you to expect it I assure you).
Some people will never even got the required 'thankyou' for nice gestures like this and this may lead them to believe that the person was not too fussed either way and vote accordingly the following year - i.e. just give a card and get the same response, or lack thereof! (but be �60 up on the deal!)
Main point is Zimzam, you would be the sort of person to text, call, email with a thankyou but not everybody is brought up with the same ideals when it comes to good manners. Take the high ground and satisfy yourself that you did a lovely gesture and your reward will come, at latest, in heaven but hopefully sooner!
Merry Christmas to you !