Problem to line

Error	2	'DocumentFormat.OpenXml.OpenXmlElement' does not contain a definition for 'Id' and no extension method 'Id' accepting a first argument of type 'DocumentFormat.OpenXml.OpenXmlElement' could be found (are you missing a using directive or an assembly reference?)	C:\App0\App5\Program.cs	170	127	App5

                        using (SpreadsheetDocument spreadSheet = SpreadsheetDocument.Open(@Path0, true))
                        {
                            ...
                            WorksheetPart worksheetPart2 = (WorksheetPart)spreadSheet.WorkbookPart.GetPartById(sheets.First().Id);

Many Thanks & Best Regards, Hua Min