The middle hole has a large wooden dowel that goes there. Two bolts, one top, one bottom. Here's what's up...the posts are swapped....the left goes right, the right goes left....yes you are missing 2 dowels, if the store doesn't have them you can get them at hardware store....it isn't a big deal to leave them out unless you have a heavy person on the bed. When I finished setting up new furniture we delivered, I left the Allen wrenches and instructions with the owner.

You can get instructions for the furniture by using the letter/numbers/manufacturer, on the outside of the box.