We prepay a material vendor. The initial invoice to establish the credit on account is charged to a prepaid GL Account. The Vendor then sends tickets for the materials ordered/used. We need to job cost these ticket amounts and reduce the prepaid account. I attempted to enter and AP invoice with a debit line to direct materials and a credit line to the prepaid account, invoice nets Zero, but Sage won't allow me to save with a zero invoice total. How should this scenario be handled?