Norton family does not shut down PC when time limit or curfew reached

I was successfully using Norton Family on our 3 home computers (2 Macs and 1 Windows) until recently.  Now when the time limit is reached on the windows machine nothing happens, my son can keep playing as long as he wishes.  I have tried changing the time limits and resaving but to no avail.  This is also the case with blocked time periods - he can access his PC whenever he wants despite me restricting his hours of use via Norton Family.  Any suggestions on what to try?  Thanks