You have to have an adult and the toddler in the bathroom next to the tub, make sure your toddler is active (has green diamond over its head), and click on the tub to take a bath for 15 minutes. As long as an adult is near the tub it will work. it took me forever to get it to work. The adult will stay in the bathroom and sit on the tub to help the todder bathe.
good luck!