I'm having an issue when trying to use an API to create lines to a selected Invoice.

The error is "You must provide a valid value for the Purchase Order Number attribute. (AP-810667)" but when i checked for the PO was opened

body: {    "LineNumber": 3,    "LineAmount": 40,    "UnitPrice": 20,    "Quantity": 2,    "LineType": "Item",    "PurchaseOrderLineNumber": 1,    "PurchaseOrderNumber": "DCO00000035",    "PurchaseOrderScheduleLineNumber": 1}

API: http://<server>/fscmRestApi/resources/11.13.18.05/invoices/300000045562473/child/invoiceLines