Mengapa status sesi tidak berfungsi

Ketika saya mengklik Tombol Tambah di halaman admin, saya ingin menampilkan jumlah unit total setiap golongan darah di halaman pengguna. Jadi di sini, saya menggunakan status sesi untuk menampilkannya, tetapi tetap saja tidak berfungsi dan tidak menunjukkan kesalahan apa pun. Saya juga membuat perubahan pada konfigurasi web.

Apa yang saya coba:

This Button is from Gridview (Admin page)

protected void Button3_Click(object sender, EventArgs e)
{
    con.Open();

    //    string query1 = "SELECT SUM(Unit) AS TotalUnit,Blood_Group FROM TableDF GROUP BY Blood_Group ";

    SqlCommand com2 = new SqlCommand("SELECT SUM(Unit) AS TotalUnit1,Blood_Group FROM TableDF GROUP BY Blood_Group ", con);



    SqlDataReader reader = com2.ExecuteReader();

    while (reader.Read())
    {
        string BloodGroup1 = reader["Blood_Group"].ToString();
        int TotalUnit1 = Convert.ToInt32(reader["TotalUnit1"]);

        Session[BloodGroup1 + "TotalUnit1"] = TotalUnit1;

    }
    reader.Close();
    con.Close();
}

This is User Page 

protected void Page_Load(object sender, EventArgs e)
        {
            if (!IsPostBack)
            {
                Label3.Visible = true;
                Label4.Visible = true;
                Label5.Visible = true;
                Label6.Visible = true;
                Label7.Visible = true;
                Label8.Visible = true;
                Label9.Visible = true;
                Label10.Visible = true;
            }

            if (Session["A+_TotalUnit"] != null)
            {
                Label3.Text = " " + Session["A+_TotalUnit"].ToString();
            }
            if (Session["A-_TotalUnit"] != null)
            {
                Label4.Text = "" + Session["A-_TotalUnit"].ToString();
            }
            if (Session["B+_TotalUnit"] != null)
            {
                Label5.Text = "" + Session["B+_TotalUnit"].ToString();
            }
            if (Session["B-_TotalUnit"] != null)
            {
                Label6.Text = " " + Session["B-_TotalUnit"].ToString();
            }
            if (Session["O+_TotalUnit"] != null)
            {
                Label7.Text = " " + Session["O+_TotalUnit"].ToString();
            }
            if (Session["O-_TotalUnit"] != null)
            {
                Label8.Text = " " + Session["O-_TotalUnit"].ToString();
            }
            if (Session["AB+_TotalUnit"] != null)
            {
                Label9.Text = "" + Session["AB+_TotalUnit"].ToString();
            }
            if (Session["AB-_TotalUnit"] != null)
            {
                Label10.Text = "" + Session["AB-_TotalUnit"].ToString();
            }

            

        }

and Web.Config changess
<system.web>
 <sessionState mode="InProc" cookieless="false" timeout="20" />

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