I always seem to get male nannies. Once you play the toddler you can get the nanny to work by letting the toddler ask for help with stuff. When one of my toddlers became a child the nanny would help with homework without the kid asking. Then when the kid started drawing or playing his piano the nanny would watch or listen and then encourage him by saying "good work" or something relevant. some of my nannies deem to want to stay too so my sim would dismiss them and then they would just come back even when the parent is at home. I let them stay sometimes because they make themselves very useful.