I have two pages main page have grid view it works fine the second page is redirect result from main page that is also work fine, but when calculate sum of selected row it does not show to the redirec

Here is the code from main page:
 private void SendGridInfo()
        {
           

            DataTable dt = new DataTable();
            DataRow dr = default(DataRow);
           
            dt.Columns.Add(new System.Data.DataColumn("Invoice Number", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Original Amount", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Remaining Amount", typeof(string)));
            dt.Columns.Add(new System.Data.DataColumn("Amount To Pay", typeof(string)));

            foreach (GridViewRow row in GridView2.Rows)
            {
                if (row.RowType == DataControlRowType.DataRow)
                {
                    CheckBox chk = (CheckBox)row.FindControl("chkSelect");
                    Label label0 = (Label)row.FindControl("Label0") as Label;
                    Label label3 = row.FindControl("Label3") as Label;
                    Label label4 = (Label)row.FindControl("Label4") as Label;
                    TextBox textbox1 = (TextBox)row.FindControl("txtRemainingAmount") as TextBox;

                    if (chk.Checked)
                    {
                        dr = dt.NewRow();
                        dr[0] = label0.Text;
                        dr[1] = label3.Text;
                        dr[2] = label4.Text;
                        dr[3] = textbox1.Text;
                        dt.Rows.Add(dr);
                    }
                }
            }
           
            Session["GridData"] = dt;
            RedirectTo("Selected Invoice");
        }
the redirected page code is:
 protected void Page_Load(object sender, EventArgs e)
        {

            if (Session["GridData"] != null)
            {
                //Response.Write(Session["lblTotal.Text"].ToString());
                DataTable dt = (DataTable)Session["GridData"];
                GridView2.DataSource = dt;
                GridView2.DataBind();
                Response.Write(Session["GridData"].ToString());
            }
        }