Not complete ServiceQueue problem that need some help,

ServiceQueue.cs

// = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = = 
// My problem description. You are welcome to comment/fork your own tried/functional versions of this.
// Appearently I have successed the queue on all needed situations. Except a trivial one, the ervice aren't really dequeue.
// The two methods below is two services that are ranned simultaneous within same application (a Windows Service).
//
// 1# As I can see, the line 'if (queue.TryDequeue(..))' never get looped/waked-up..
// = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = =  = = = = = 


// The object that will Enqueue, put object into Queue (can be put into a console application)
//
        public void Start()
        {
            isListening = true;
            Thread listener = new Thread(() =>
            {
                while (isListening)
                {
                    receivedStream = udpClient.Receive(ref endPoint);
                    try
                    {
                        EchoToSender(receivedStream, endPoint);

                        request = new Datagram.Request();
                        request = Deserialize(receivedStream);
                        queue.Enqueue(request);
                    }
                    catch (SocketException ex)
                    {
                        WriteToFile(ex.ToString());
                        break;
                    }
                    catch (Exception ex)
                    {
                        WriteToFile(ex.ToString());
                        break;
                    }
                }
            });
            listener.IsBackground = true;
            listener.Start();
        }


//
// Dequeue service. This method will take "next object in queue" (can be put into a console application)
//
        public void Start()
        {
            Thread listener = new Thread(() =>
            {
                new Datagram.Request packet;
                while (true)
                    if (queue.TryDequeue(out packet, new Random().Next(20)))
                        packet = (Datagram.Request)queue.Dequeue();
            });

            listener.IsBackground = true;
            listener.Start();
        }


//
//
//
// This is the Queue service itself. ServiceQueue.cs 
// 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;

namespace ServiceName
{
    public class ServiceQueue<T> where T : class
    {
        private bool isClosing;
        private readonly Queue<T> queue = new Queue<T>();
        private readonly int maxSize;

        public bool Enqueue(T item)
        {
            lock (queue)
            {
                if (isClosing || null == item)
                    return false;

                while (queue.Count >= maxSize)
                    Monitor.Wait(queue);

                queue.Enqueue(item);

                if (queue.Count > 0)
                    Monitor.PulseAll(queue);

                return true;
            }
        }

        public T Dequeue()
        {
            T item;
            lock (queue)
            {
                while (queue.Count == 0)
                    Monitor.Wait(queue);

                item = queue.Dequeue();

                if (queue.Count > 0)
                    Monitor.PulseAll(queue);

                return item;
            }
        }

        public bool TryDequeue(out T value)
        {
            lock (queue)
            {
                while (queue.Count == 0)
                {
                    if (isClosing)// !Monitor.Wait(queue, timeout))
                    {
                        value = default(T);
                        return false;
                    }
                    Monitor.Wait(queue);
                }

                value = queue.Dequeue();

                if (queue.Count == maxSize - 1)
                {
                    //wake up blocking enqueue
                    Monitor.PulseAll(queue);
                }
                return true;
            }
        }


        public void Close()
        {
            lock (queue)
            {
                if (!isClosing)
                {
                    isClosing= true;
                    queue.Clear();
                }
            }
        }

        public void Clear()
        {
            lock (queue)
            {
                queue.Clear();
                Monitor.Pulse(queue);
            }
        }

        public int Count
        {
            get
            {
                lock (queue)
                {
                    return queue.Count;
                }
            }
        }

        public ServiceQueue()
        {
            this.maxSize = 500;
            lock (queue)
            {
                isClosing = false;
                Monitor.PulseAll(queue);
            }
        }

    }
}