WMS Confirm outbound shipment

Hi all,
I'm trying to confirm an outbound shipment, it is part of a group of 6 shipments belonging to one wave. Five shipments were already shipped, but this one shows: Some of the items that are needed for load IDC00002416 have not yet been picked and moved to the final shipping location.

All the works are closed, and also are the containers done for the packing process… what other reason could be for this message?