Woah, that enclosure is WAY too big for a young bp. (I almost think it's too big for an adult even, an adult would fit in a 20g nicely but preferably a 30g)
He's probably not going to eat until you get him in a properly sized enclosure.
Also, why did you wait 11 days to feed again? That young of a ball python should be on a 5-7 day feeding schedule.

Are you feeding live? And yes, a good idea would also be to try feeding at dusk or night.

What are your temps, humidity, exc?