Why can't I get 'project invoice' to work? December 03, 2019 08:52 Updated Follow PROJECT INVOICE CANNOT BE USED. It does not work for work in progress and cannot aggregate. Read more here (use chrome translate). Related articles Which cost price are inventory items posted with, when added in an inventory journal at a cost price of 0? Report Generator: My fields do not appear when I re-print orders and invoices.