If you give yourself items with the give command and there is an item in slot 1 the next item you give yourself will skip slot 2 and go into slot 3.

What I Expected To Happen Was: When you give yourself an item when there is already an item in slot 1, that item would go into slot 2.

What Actually Happened Was: If there is an item in slot 1 and you give yourself another item that item will be put in slot 3.

Edit: Never mind it seems to work now.