sims 3 why did my childs imaginary friend dissapear?

Question

I had received an imaginary friend doll in the mail and immediately put it in my newborns crib. im not sure if by this time they can grow a relationship with them or not. But when my child grew into a toddler, the imaginary freind whent missing. I checked every member of the household's inventory and even checked if it would be in the crib with my toddler. I still havent found it and don't know how to get it back. PLEASE HELP!!!