private static WorksheetPart getWorkSheetPart(WorkbookPart workbookPart, DefinedNameVal definedName) { //get worksheet based on defined name string relId = workbookPart.Workbook.Descendants<Sheet>() .Where(s => definedName.SheetName.Equals(s.Name)) .First() .Id; return (WorksheetPart)workbookPart.GetPartById(relId); }