ODP.Net Unable to receive OracleDependency Notifications

Question

I am trying to get a notification in ASP.Net console application whenever a column value changes in a specific database column using OracleDependency. Notification gets Registered and inserted in USER_CHANGE_NOTIFICATION_REGS table but onChange event is not triggered when row is updated in DB.

Additionally, I have granted following privilege to user:

grant change notification to hasan;

and my firewall is also currently disabled.

Below is the code to register query:

string constr = "User ID=hasan;Data Source=10.32.157.5:1521/iwin;Password=hasan; Min Pool Size=1; Connection Lifetime = 120;";
            OracleConnection con = null;
            OracleDependency dep = null;

            con = new OracleConnection(constr);
            OracleCommand cmd = new OracleCommand("select * from hasan.Emp", con);
            con.Open();

            OracleDependency.Port = 2010;
            dep = new OracleDependency(cmd);
            dep.OnChange +=
              new OnChangeEventHandler(OnMyNotificaton);
            OracleDataAdapter ad = new OracleDataAdapter(cmd);
            cmd.ExecuteNonQuery();              
            OracleTransaction txn = con.BeginTransaction();                
            string updateCmdText =
              "update hasan.Emp empl set empl.empId = empl.empId + 1";
            OracleCommand updateCmd = new OracleCommand(updateCmdText, con);                
            updateCmd.ExecuteNonQuery();              
            txn.Commit();

Event Listener:

 public static void OnMyNotificaton(object src,
      OracleNotificationEventArgs arg)
        {
            Console.WriteLine("Notification Received");
            DataTable changeDetails = arg.Details;
            Console.WriteLine("Data has changed in {0}",
              changeDetails.Rows[0]["ResourceName"]);
            IsNotified = true;
        }