Not getting values of DACExtension

I am fetchig data from the DB. And I to show a read-only field in a shipment screen.

var worksheet = from p in graph.Select<SOPickingWorksheet>()
                                           join q in graph.Select<SOPickingWorksheetShipment>() on p.WorksheetNbr equals q.WorksheetNbr
                                           where q.ShipmentNbr == row.ShipmentNbr
                                           select p;
            SOPickingWorksheet tempWrksheet = worksheet.FirstOrDefault();
            SOPickingWorksheetExt worksheetExt = tempWrksheet.GetExtension<SOPickingWorksheetExt>();

I am getting correct worksheet from the query but my worksheetExt variable does not have the value stored in DB table. Can anyone help me here. I am writing all of this code in SOShipmentEntry GraphExtension.