预处理器指令必须显示为行上的第一个非空格字符

我收到错误Preprocessor directives must appear as the first non-whitespace character on a line.我需要在代码中更改什么才能使其工作？

protected void Button3_Click(object sender, EventArgs e)
    {
        DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[21] { new DataColumn("Siebel_SR#"),
          new DataColumn("Siebel_SR#1"), new DataColumn("Tran_Qty"), new DataColumn("Ord_Sou_Ref"),
          new DataColumn("Tran_Reference"), new DataColumn("[Ord Number]"), new DataColumn("[Ord Number1]"),
          new DataColumn("Transaction_Type_Id"), new DataColumn("Trans_Date"), new DataColumn("[Trans Sub]"),
          new DataColumn("Business"), new DataColumn("New_DFF_SR#"), new DataColumn("Reason_Name"),
          new DataColumn("Line_Type"), new DataColumn("Org"), new DataColumn("Sub_Inv"), new DataColumn("Part_Num"),
          new DataColumn("[Last Updated By]"), new DataColumn("[Created By]"), new DataColumn("Employee"), new DataColumn("DateWorked") }); 
        foreach (GridViewRow row in GridView1.Rows)
        {
            if (row.RowType == DataControlRowType.DataRow) 
            {
                CheckBox chk = (row.Cells[0].FindControl("chkSelect") as CheckBox);
                if (chk.Checked)
                {
                    string Siebel_SR# = row.Cells[2].Text;
                    string Tran_Qty = row.Cells[3].Text;
                    string Ord_Sou_Ref= row.Cells[4].Text;
                    string Tran_Reference = row.Cells[5].Text;
                    string Transaction_Type_Id = row.Cells[8].Text;
                    string Trans_Date = row.Cells[9].Text;
                    string Business = row.Cells[11].Text;
                    string Reason_Name = row.Cells[13].Text;
                    string Line_Type = row.Cells[14].Text;
                    string Org = row.Cells[15].Text;
                    string Sub_Inv = row.Cells[16].Text;
                    string Part_Num = row.Cells[17].Text;

                    string Employee = row.Cells[20].Text;
                    string DateWorked = row.Cells[21].Text;
                    dt.Rows.Add( Tran_Qty ,Ord_Sou_Ref , Tran_Reference , Transaction_Type_Id, Trans_Date ,
                     Business , Reason_Name ,Line_Type , Org , Sub_Inv , Part_Num , Employee , DateWorked  );
                }
            }
        }
        GridView3.DataSource = dt;
        GridView3.DataBind();
    }