We've been having trouble getting B to STTN in his crib.

He's STTN for several weeks while in his RNP. Last week, we tried moving him to his crib at the recommendation of his pediatrician. For some reason, he won't STTN in there!

Without fail, he wakes up in the middle if the night screaming. Once, he had his leg stuck in the slats, but there is no apparent reason for the others. He isn't hungry as we can just pick him up, bounce him, and he will drift right back to sleep in his RNP until morning. If we try to put him back down in his crib he will wake again.

Is this normal? Any tips for keeping him in the crib all night?