How to get total Page Number of a subreport in Crystal report

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.NET

CrystalReports

private int SubreportTotelPage(CrystalReportViewer CrvViewer)
 {
   int TotalPage = 0;
   ReportDocument reportDocument = ((ReportDocument)CrvViewer.ReportSource);
  Sections sections = reportDocument.ReportDefinition.Sections;
  foreach (Section section in sections)
      {
        ReportObjects reportObjects = section.ReportObjects;
            foreach (ReportObject reportObject in reportObjects)
            {
               if (reportObject.Kind == ReportObjectKind.SubreportObject)
                 {
                   SubreportObject subreportObject = (SubreportObject)reportObject;
                            if (subreportObject.SubreportName == "Sub_Memorandum.rpt")
                            {
 CrystalDecisions.CrystalReports.Engine.TextObject rptTxtGroup = subReportDocument.ReportDefinition.ReportObjects["Text9"] as CrystalDecisions.CrystalReports.Engine.TextObject;
                                if (rptTxtGroup != null)
                                    return TotalPage = Convert.ToInt16
(rptTxtGroup.Text.ToString());

                         /*       CrystalDecisions.CrystalReports.Engine.FieldObject rptFieldGroup = (subReportDocument.ReportDefinition.ReportObjects["{@NoofPageinSubReport}"] as CrystalDecisions.CrystalReports.Engine.FieldObject);
                                if (rptFieldGroup != null)
                                    return TotalPage = Convert.ToInt16(rptFieldGroup.ToString()); */
                                else
                                    return TotalPage;
}

In Report preview report Function NoofPageinSubReport show correct value ie 6
but the C# function return text "@NoofPageinSubReport"

when i am using CrystalDecisions.CrystalReports.Engine.FieldObject
it return "@NoofPageinSubReport" text ... ie
WhilePrintingRecords;
Shared numberVar TotalPageSubreport;
TotalPageSubreport:=PageNumber as out put.