Windows Phone 7 Navigation

Question

I am having a problem with navigating between a MainPage and a details Page.

On the main page the code looks like this:

private void MainPage_Loaded(object sender, RoutedEventArgs e)
    {
          State.Clear();
          List<Level> lst = new List<Level>();
          using (SqliteCommand selectCmd = Constants.conn.CreateCommand())
          {
              Constants.conn.Open();
              selectCmd.Transaction = Constants.conn.BeginTransaction();
              selectCmd.CommandText = " SELECT * FROM Levels";

              using (SqliteDataReader reader = selectCmd.ExecuteReader())
              {

                  while (reader.Read())
                  {
                      Level lev = new Level();
                      lev.ID = Convert.ToInt32(reader.GetValue(0));
                      lev.Name = reader.GetValue(1).ToString();
                      lev.levelScore = Convert.ToInt32(reader.GetValue(2));
                      lst.Add(lev);
                  }
              }
              selectCmd.Transaction.Connection.Close();
          }
          Constants.conn.Close();
          levelList.ItemsSource = lst;

        }

It sets the items on the page. I navigate on the detail page. The problem comes when I navigate back to the MainPage... Although the State is Clear and the levelItems is 0 It renders The previous view of the page and when it tries to access the sqlConnection throwsan exception.