Sleeping in the crib

Hannah

So my son is four months old and we are having one heck of a time trying to get him to sleep in his crib. He sleeps in a bassinet next to me at night time but I’m trying to get him used to his crib by doing naps during the day in his crib and I rock him to sleep and I put him in there and the minute I put him down he just screams and he will not stay asleep what can I do???!