Problème avec les threads c#

   public partial class Form1 : Form
    {
        static int numberOfThreads = 10;
        static int number = 1;
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Task<bool>[] tasks = new Task<bool>[numberOfThreads];
            for (int i = 0; i < numberOfThreads; ++i)
            {
                int j = i;
                checked
                {
                    tasks[i] = Task<bool>.Run(() => { return IsPrimeInRange(number, number * j / numberOfThreads, number * (j + 1) / numberOfThreads); });
                }
            }

            Task.WaitAll(tasks);
        }

        private static bool IsPrimeInRange(long number, long start, long end)
        {
            for (long i = Math.Max(start, 2); i < end; i = ++i)
            {
                if (number % i == 0L)
                {
                  MessageBox.Show("");
                }
            }

            return true;
        }

    
    }

  public static void add_c(RichTextBox rich string text, Color color, bool pi = true)
        {
            rich.Invoke((Action)delegate
            {

                rich.SelectionStart = rich.TextLength;
                rich.SelectionLength = 0;

                if(pi == true)
                {
                    rich.SelectionColor = Color.Gray;
                    rich.AppendText(">< ");
                } 

                rich..SelectionColor = color;
                rich.AppendText(text + Environment.NewLine);
                rich.SelectionColor = box.ForeColor;

                rich.ScrollToCaret();

            });
        }

    public class TexteEnCouleur
    {
        public string Texte { get; set; }

        public Color Couleur { get; set; }
    }

while (queue.TryDequeue(out number))
                {
  var lixn = htcli.GetAsync(solo + number).Result;
                page++;

                  add_c(list, "(" + page + "/" + page_tot + ") > " + lien, Color.Red);


                    if (lixn.StatusCode == HttpStatusCode.OK)
                    {
                        //add_c(list, lien, Color.Green);
                       monSacConcurrent.Add(new TexteEnCouleur { Texte = "LeTexte", Couleur = Color.Green  });
                       AfficheResultat();
                    }
}

        private void AfficheResultat()
        {
            rich.Invoke((Action)delegate
            {

                rich.Clear();
                List<TexteEnCouleur> listeTriee = monSacConcurrent.OrderBy(x => x.Texte).ToList();

                foreach(TexteEnCouleur texte in listeTriee)
                {
                    //ici le code pour remplir le richtextbox
                }

            });
        }

static string[] lines = File.ReadAllLines(@"text_file.txt");
     static HttpClient http = new HttpClient();
        static string number;
        static int page = 0;
        static ConcurrentBag<string> myBag = new ConcurrentBag<string>(lines);
        static int page_tot = myBag.Count();

        public class TexteEnCouleur
        {
            public  string Texte { get; set; }

            public Color Couleur { get; set; }
        }

 private void AfficheResultat()
        {
            richTextBox1.Clear();
            List<TexteEnCouleur> listeTriee = myBag.OrderBy(x => x.Texte).ToList();

            foreach (TexteEnCouleur texte in listeTriee)
            {
                //ici code pour remplir le richtextbox
            }

        }

 private void scan()
        {
                       string lien = "http://www.google.fr/";
            while (myBag.TryTake(out number))
            {
                var lixn = http.GetAsync(lien + number).Result;
                page++;

                richTextBox1.AppendText("(" + page + "/" + page_tot + ") > " + lien);


                if (lixn.StatusCode == HttpStatusCode.OK)
                {
                    myBag.Add(new TexteEnCouleur { Texte = "LeTexte", Couleur = Color.Green });
                    AfficheResultat();
                }
            }