Huh? Really? wonder why I haven't seen them on the shelves at my local barnes and noble, then.
Three possibilities
A) Store copies already purchased and they are awaiting restock. Did you check to see if they had them on re-order at the desk? Also some smaller stores may only be assigned so many copies and no auto restock code, so once sold they do not replenish unless specifically requested by customer.
B) Smaller stores (C, D & E sized) have less shelf space and may or may not get every new release, based on a crazy formula headquarters uses to distribute the books. I used to work at B&N and sometimes the logic of what goes on the shelf automatically can drive you crazy trying to figure it out.
C) They got nicked or may already be reserved for someone and the since the system still shows them as 'in stock' until an inventory check, the system would not be restocking it automatically.
But in either case you should still be able to go to the desk and request them to order it in for you and only takes a few days to come in unless the warehouse is out and awaiting a restock.