C# - MS Word - MailMerge how to get Last Record when MailMerge.DataSource.LastRecord returns -16 -

unable last record using mailmerge.datasource.lastrecord or mailmerge.datasource.recordcount first variable returns -16 , second 1 returns -1.

cause:
.lastracord , .recordcount returning -16 , -1 because reading data csv file.

solution: following code return last record or record count reading dataset csv file or text file.

public int getmailmergelastrecord()  {        document doc = globals.addin.activedocument;              // storing current record        int currentrec = (int)doc.mailmerge.datasource.activerecord;         //getting last record        int lastrecord = 1;        doc.mailmerge.datasource.activerecord = (doc.mailmerge.datasource.activerecord - (int)doc.mailmerge.datasource.activerecord) + int32.maxvalue;        lastrecord =  (int)doc.mailmerge.datasource.activerecord;         // resetting current record above line of codes change active record last record.        doc.mailmerge.datasource.activerecord = (doc.mailmerge.datasource.activerecord - (int)doc.mailmerge.datasource.activerecord) + currentrec;        return lastrecord; } 

note
above code word application level addin