If you are with the Depot Box opened and use Container.GetLast():Name() u will see that the right way to type this containers names are: "Depot Box Number", and capital letters does matter.
As the Depot Box have IDs 22797, 22798, 22799 and so on, you can make a function to do like: Container.OpenDPBox(num), or UseItem(22796 + num, true) and the 'num' you just do 22796 + 'num'.