Is your son the only user on this computer? If so, this is actually the wrong set up.
In order for family safety to work properly, the computer should have been set up with the organizer user first as admin, then enable to child's account after that.
To correct this, see if you can do this on his computer first:
hold down win+r keys , type in netplwiz and press enter. let me know if it lets you launch that.