Why data is not featching

if (Page.IsValid == true)
        {
            string sc1 = "";

            if (rbStudent.Checked == true)
            {
                sc1 = "Student";
            }
            if (rbPFaculty.Checked == true)
            {
                sc1 = "Private Faculty";
            }
            if (rbSFaculty.Checked == true)
            {
                sc1 = "School Faculty";
            }


            SqlConnection CON = new SqlConnection(System.Web.Configuration.WebConfigurationManager.ConnectionStrings["tuitionConnectionString"].ConnectionString);
            SqlTransaction tr = null;
            CON.Open();
            tr = CON.BeginTransaction();
            ds = new DataSet();
            string sql = "select *  from registration";
            da = new SqlDataAdapter(sql, CON);
            da.Fill(ds, "registration");
            //string sa = txtSess.Text;
            //txtFname.Text = sa;
            if (Session["name"] != null)
            {
                string sa = Session["name"].ToString();

                int r = 0;
                DataRow[] rs;
                rs = ds.Tables["registration"].Select("email='" + sa + "'");
                r = rs.Length;
                if (r > 0)
                {
                    //FETCH DATA FROM DATABASE
                    DataRow dr;
                    dr = rs[0];
                    txtFname.Text = dr["fname"].ToString();
                    txtLname.Text = dr["lname"].ToString();
                    txtDob.Text = dr["dob"].ToString();
                    txtCno.Text = dr["cont"].ToString();
                    sc1 = dr["rtype"].ToString();
                    ddClass.SelectedItem.Text = dr["tclass"].ToString();
                    txtSchool.Text = dr["school"].ToString();
                    ddBoard.SelectedItem.Text = dr["board"].ToString();
                    ddCity.SelectedItem.Text = dr["city"].ToString();
                    txtPCode.Text = dr["pcode"].ToString();
                    ddState.SelectedItem.Text = dr["state"].ToString();

                    try
                    {

                        //UPDATE RECORDS in DataBase

                        com = CON.CreateCommand();
                        com.CommandText = "UPDATE registration SET fname='" + txtFname.Text + "',lname='" + txtLname.Text + "',dob='" + txtDob.Text + "',cont='" + txtCno.Text + "',rtype='" + sc1.ToString() + "',tclass='" + ddClass.SelectedItem.Text + "',school='" + txtSchool.Text + "',board='" + ddBoard.SelectedItem.Text + "',city='" + ddCity.SelectedItem.Text + "',pcode='" + txtPCode.Text + "',state='" + ddState.SelectedItem.Text + "' WHERE email='" + txtSess.Text + "'";
                        try
                        {
                            com.ExecuteNonQuery();
                            System.Web.UI.WebControls.Label lbl1 = new System.Web.UI.WebControls.Label();
                            lbl1.ForeColor = System.Drawing.Color.Yellow;
                            lbl1.BackColor = System.Drawing.Color.Blue;
                            lbl1.Text = "Your record UPDATED sucessfully";
                            ph1.Controls.Add(lbl1);
                        }
                        catch (Exception ex)
                        {
                            Response.Write(ex.Message);
                        }

                         }
                    catch (Exception ex)
                    {

                        Response.Write("" + ex);
                        tr.Rollback();
                    }

                    finally
                    {
                        CON.Close();
                    }
                }
            }
        }