action prepare invoice Error: An error occurred during processing of the field Project/Contract value PR00000006 Error: Project/Contract 'PR00000006' cannot be found in the system. Please verify whether you have proper access rights to this object.

i need help for this bug action prepare invoice in Shipment Screen (SO302000)

in Shipment Screen, Project Field and Project Task Field is customize.
this is source code for Project and project task

 protected void SOShipment_RowPersisting(PXCache cache, PXRowPersistingEventArgs e, PXRowPersisting InvokeBaseHandler)
    {
      if(InvokeBaseHandler != null)
        InvokeBaseHandler(cache, e);
      var row = (SOShipment)e.Row;
      if (row == null) return;
      //if((e.Operation & PXDBOperation.Command )== PXDBOperation.Insert)
      //{
          var rowExt = PXCache<SOShipment>.GetExtension<SOShipmentExt>(row);

          SOOrderShipment shipOrder = PXSelect<SOOrderShipment,
                  Where<SOOrderShipment.shipmentNbr, Equal<Required<SOOrderShipment.shipmentNbr>>>>
                  .Select(this.Base, row.ShipmentNbr);

          if(shipOrder != null ){
            SOOrder order = PXSelect<SOOrder,
                  Where<SOOrder.orderNbr, Equal<Required<SOOrder.orderNbr>>>>
                  .Select(this.Base, shipOrder.OrderNbr);

            if(order != null ){

              SOLine line = PXSelect<SOLine,
                  Where<SOLine.orderNbr, Equal<Required<SOLine.orderNbr>>>>
                  .Select(this.Base, order.OrderNbr);

              PMProject prj = PXSelect<PMProject,
                    Where<PMProject.contractID, Equal<Required<PMProject.contractID>>>>
                    .Select(this.Base, order.ProjectID);
              if(prj.ContractCD != null){
                rowExt.UsrzProjectNumb = prj.ContractCD;
              }

              if(line.TaskID != null && prj.ContractID != null ){
                PMTask task = PXSelect<PMTask,
                                Where<PMTask.projectID, Equal<Required<PMTask.projectID>>,
                                And<PMTask.taskID, Equal<Required<PMTask.taskID>>>>>
                                .Select(this.Base, prj.ContractID, line.TaskID);
                if(task.TaskCD != null){
                  rowExt.UsrzProjectTask = task.TaskCD;
                }
              }
            }
          }

      //}

    }

anyone know how to solved this bug ? thanks