Session Issue- Value of session changing in next page

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;


using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.SqlClient;


public partial class xfianlexam : System.Web.UI.Page
{
    SqlCommand cmd1;
    public string qnum;
    public string Ans = null;
    public int tNUM;
    protected void Page_Load(object sender, EventArgs e)
    {
        lblStuNum.Text = Session["id"].ToString();
        SqlConnection cn = myClass.DBCon();
        cn.Open();
        SqlCommand c = new SqlCommand("select * from student where snum='" + Session["id"].ToString() + "'", cn);

        SqlDataReader r = c.ExecuteReader();

        r.Read();
        lblStuName.Text = r["sname"].ToString();
        Session["sname"] = lblStuName.Text;

        cn.Close();
        
        
        SqlConnection scn = myClass.DBCon();
        scn.Open();
        SqlCommand cmd2 = new SqlCommand("select * from course where courseid='" + Session["courseid"].ToString() + "'", scn);
        SqlDataReader ssr = cmd2.ExecuteReader();

        ssr.Read();
        lblCourseid.Text = ssr["courseid"].ToString();
        Session["courseid"] = lblCourseid.Text;


        scn.Close();



        Session["name"] = lblStuName.Text;
    

        int i = 1;
       SqlConnection con = myClass.DBCon();
        
        con.Open();
      
          const int Total = 10;
            ArrayList lstNumbers = xfianlexam.RandomNumbers(Total);

            for (int i1= 0; i1 < lstNumbers.Count; i1++)
            {

               
                cmd1 = new SqlCommand("select * from Question where Courseid='" + Session["courseid"].ToString() + "'and questOrder='" + lstNumbers[i1] + "'", con);
               
                SqlDataReader sdr = cmd1.ExecuteReader();
                while (sdr.Read())
                {
                    
                    Literal littxt = new Literal();
                    Literal litti = new Literal();

                    RadioButtonList cbk = new RadioButtonList();
                    cbk.ID = "cbk" + i.ToString();
        littxt.Text = "<font style="background : #FFF8C6;">" +i.ToString() + "、" + Server.HtmlEncode(sdr["Quest"].ToString())+"</font><br><blockquote>";
                    litti.Text = "</blockquote>";
                   

                    qnum = i.ToString();
                    Session["qnum"] = qnum;
                    cbk.Items.Add("A. " + Server.HtmlEncode(sdr["opt1"].ToString()));
                    cbk.Items.Add("B. " + Server.HtmlEncode(sdr["opt2"].ToString()));
                    cbk.Items.Add("C. " + Server.HtmlEncode(sdr["opt3"].ToString()));
                    cbk.Items.Add("D. " + Server.HtmlEncode(sdr["opt4"].ToString()));
                    cbk.Font.Size = 11;
                    for (int j = 1; j <= 4; j++)
                    {
                        cbk.Items[j - 1].Value = j.ToString();
                    }


                    Label7.Text += sdr["corAns"].ToString();
                    Ans += sdr["corAns"].ToString();


                    Label5.Text = Ans.ToString();
                
                         Session["Ans"] = Ans;
                  
                    Panel2.Controls.Add(littxt);
                    Panel2.Controls.Add(cbk);
                    Panel2.Controls.Add(litti);

                    i++;
                    tNUM++;

                    
                }

                sdr.Close();
                //sdr10.Close();
                cn.Close();
            }
        Label8.Text = Label5.Text;
        

      


        }

    public static ArrayList RandomNumbers(int max)
    {
        // Create an ArrayList object that will hold the numbers
        ArrayList lstNumbers = new ArrayList();
        // The Random class will be used to generate numbers
        Random rndNumber = new Random();

        // Generate a random number between 1 and the Max
        int number = rndNumber.Next(1, max + 1);
        // Add this first random number to the list
        lstNumbers.Add(number);
        // Set a count of numbers to 0 to start
        int count = 0;

        do // Repeatedly...
        {
            // ... generate a random number between 1 and the Max
            number = rndNumber.Next(1, max + 1);

            // If the newly generated number in not yet in the list...
            if (!lstNumbers.Contains(number))
            {
                // ... add it
                lstNumbers.Add(number);
            }

            // Increase the count
            count++;
        } while (count <= 10 * max); // Do that again

        // Once the list is built, return it
        return lstNumbers;
    }
    protected void Finish_Click(object sender, EventArgs e)
    {


    }
  
        protected void ibtnFin_Click(object sender, EventArgs e)
    {
     
        string msc = "";
        for (int i = 1; i <= tNUM; i++)
        {
            RadioButtonList list = (RadioButtonList)Panel2.FindControl("cbk" + i.ToString());
            if (list != null)
            {
                if (list.SelectedValue.ToString() != "")
                {

                    msc += list.SelectedValue.ToString();
                }
                else
                {
                    msc += "0";
                }
            }
        }
        Session["Sans"] = msc;
        //----------------------------
        Label9.Text = msc;
        Session["snum"] = lblStuNum.Text;
              SqlConnection cn = myClass.DBCon();
        cn.Open();
        string sno = lblStuNum.Text;
            SqlConnection cn2 = myClass.DBCon();

        cn2.Open();
        SqlCommand cmd = new SqlCommand("select count(*) from result where sname='" + Session["sname"].ToString() + "' and courseid='" + Session["courseid"].ToString() + "'", cn2);
        int i1 = Convert.ToInt32(cmd.ExecuteScalar());

        if (i1 > 0)
        {
            Response.Write("<script language='javascript'>alert('You have already participated in this examination');</script>");
            Response.Redirect("studHome.aspx");
        }
        else
        {
            SqlDataSource sds1 = new SqlDataSource();

            sds1.ConnectionString = ConfigurationManager.ConnectionStrings["examConnectionString"].ToString();

            lblStuNum.Text = Session["id"].ToString();
            sds1.InsertCommand = "insert into result(sname,courseid) values (@sname,@courseid)";

            sds1.InsertParameters.Add("sname", Session["sname"].ToString());
            sds1.InsertParameters.Add("courseid", Session["courseid"].ToString());
          





            int rowsAffect = sds1.Insert();

       
            Response.Redirect("stuResult.aspx?BInt=" + tNUM.ToString());

        }
        
    }


        protected void btnsubmit_Click(object sender, EventArgs e)
        {

        }
}