here is already an open DataReader associated with this Command which must be closed first.

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C#

i am making a webmethod in asmx.... but whenever i run this method i will get this error... i want to add manually row in dataset,with the help of datareader

[WebMethod]
    public DataSet newleger(string accno, string fromdate, string todate)
{
    SqlConnection con = new SqlConnection(@"Data Source=123-PC;Initial Catalog=bcounts;Persist Security Info=True;User ID=Saba;Password=123");
    con.Open();
    SqlCommand cmd = new SqlCommand("select gt.Value_Date,gt.Voucher_no+'-'+gr.VchrType as voucher,gt.Acct_Nirration,gr.InstrumentNo,gt.Dr_Amount,gt.Cr_Amount  from gl_transaction gt, Gl_Ref gr where gt.Accountno = '" + accno + "'  and gt.Voucher_No=gr.Voucher_no  and gt.Value_Date between '" + fromdate + "' and '" + todate + "'", con);
    SqlDataAdapter adp = new SqlDataAdapter(cmd);
        SqlDataReader rdr = cmd.ExecuteReader();
    decimal crsum = 0;
    decimal drsum = 0;
    decimal balance = 0;
    DataSet ds = new DataSet("Ledger");;
       adp.Fill(ds);
    if (rdr.HasRows)
    {
        while (rdr.Read())
        {
            if (rdr.GetDecimal(4) > 0)
            {
                balance = balance + rdr.GetDecimal(4);
                drsum += rdr.GetDecimal(4);
                DataRow dr = ds.Tables[0].NewRow();
                dr[0] = rdr.GetDateTime(0).ToShortDateString();
                dr[1] = rdr.GetString(1);
                dr[2] = rdr.GetString(2);
                dr[3] = rdr.GetString(3);
                dr[4] = rdr.GetDecimal(4).ToString();
                dr[5] = "-";
                ds.Tables[0].Rows.Add(dr);

                //data.Add(new datalist7(rdr.GetDateTime(0).ToShortDateString(), rdr.GetString(1), rdr.GetString(2), rdr.GetString(3), rdr.GetDecimal(4).ToString(), "-", balance.ToString()));
            }
            else
            {
                balance = balance - rdr.GetDecimal(5);
                crsum += rdr.GetDecimal(5);
                DataRow dr = ds.Tables[0].NewRow();
                dr[0] = rdr.GetDateTime(0).ToShortDateString();
                dr[1] = rdr.GetString(1);
                dr[2] = rdr.GetString(2);
                dr[3] = rdr.GetString(3);
                dr[4] = "-";
                dr[5] = rdr.GetDecimal(5).ToString();
                ds.Tables[0].Rows.Add(dr);
                
               // data.Add(new datalist7(rdr.GetDateTime(0).ToShortDateString(), rdr.GetString(1), rdr.GetString(2), rdr.GetString(3), "-", rdr.GetDecimal(5).ToString(), balance.ToString()));
            }
        }

        DataRow dd = ds.Tables[0].NewRow();
        dd[0] = "-";
        dd[1] = "-";
        dd[2] = "-";
        dd[3] = "-";
        dd[4] = drsum.ToString();
        dd[5] = crsum.ToString();
        //data.Add(new datalist7("-", "-", "-", "-", drsum.ToString(), crsum.ToString(), "-"));
    }

    con.Close();
    return ds;





}