Sometimes when you close your auction there are not any invoices generated and your auction items will still be in an open status. This is a rare occurrence but there is an easy fix for it.
Select the settings gear wheel next to your auctions name.
Then go to the financial tab and select the regenerate receipts button.
After you have regenerated receipts you can then update the auction and your items will be marked sold and you can view and charge the invoices.