Purchase Order Approval results in Error: The project status does not allow creation of new transact

A purchase order has 3 lines that are cancelled. Each of the lines are charged to a Project. Transactions to be charged to the project was end dated on March 31, 2018. The Buyer now needs to add 2 new lines to the PO (4 and 5). These 2 lines are not charged to a project. When the Buyer tires to approve the PO, the following 3 errors  (I assume for the first 3 lines that are cancelled) Error: The project status does not allow creation of new transactions. The PO can not be approved. Why is the system looking