[C#]Ping Problem

        public string proxyip(int index)
        {
            return Proxyview.Items[index].SubItems[0].Text.ToString() + ":" + Proxyview.Items[index].SubItems[1].Text.ToString();//
        }


public void Proxychecken(object Index)
        {
            while (isruning)
            {
                proyzahl++;
                if (proyzahl == Proxyview.Items.Count)
                {
                    isruning = false;
                    proyzahl = 1;
                    MessageBox.Show("Fetig");
                }
                string aIP = "";
                if (Proxyview.InvokeRequired)
                {
                    try
                    {
                        aIP = Proxyview.Invoke(new Proxydatenbekommen(proxyip), proyzahl).ToString();
                        Ping pingSender = new Ping();
                        PingOptions options = new PingOptions();
                        options.DontFragment = true;
                        string data = "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa";
                        byte[] buffer = Encoding.ASCII.GetBytes(data);
                        int timeout = 120;
                        PingReply reply = pingSender.Send(aIP, timeout, buffer, options);
                        if (reply.Status == IPStatus.Success)
                        {
                            MessageBox.Show("Complete");
                        }
                    }
                    catch
                    {
                    }
                }
                else
                {
                    isruning = false;
                }
            }
        }