我写了一个程序，运行起来发现不对，请高手赐教
发送端
private void StartSend()
            {
                int PacketSize = int.Parse(this.textBox6.Text);
                //数据包
                byte[] data = new byte[PacketSize];
                //创建一个文件对象
                FileInfo EzoneFile = new FileInfo(this.textBox1.Text);
                //打开文件流
                FileStream EzoneStream = EzoneFile.OpenRead();
                //包的大小
               
                //包的数量
                int PacketCount = (int)(EzoneStream.Length / ((long)PacketSize));
                this.textBox8.Text = PacketCount.ToString();
                this.progressBar1.Maximum = PacketCount;
                //最后一个包的大小
                int LastDataPacket = (int)(EzoneStream.Length - ((long)(PacketSize * PacketCount)));
                this.textBox9.Text = LastDataPacket.ToString();
                //创建一个网络端点
                EndPoint ipep = new IPEndPoint(IPAddress.Parse("127.0.0.1") , int.Parse(this.textBox5.Text));
                //创建一个套接字
                Socket server = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);           
               
                //开始循环发送数据包
                for (int i = 0; i < PacketCount; i++)
                {
                    //从文件流读取数据并填充数据包
                    EzoneStream.Read(data, 0, data.Length);                  
                    server.SendTo(data, ipep);
                    //显示发送数据包的个数
                    this.textBox10.Text = ((int)(i + 1)).ToString();
                    //进度条值的显示
                    this.progressBar1.PerformStep();
                }

                //如果还有多余的数据包,则应该发送完毕!
                if (LastDataPacket != 0)
                {
                    data = new byte[LastDataPacket];
                    EzoneStream.Read(data, 0, data.Length);               
                    server.SendTo(data, ipep);
                    this.progressBar1.Value = this.progressBar1.Maximum;
                }

                //关闭套接字
               
                server.Close();
                //关闭文件流
                EzoneStream.Close();
                this.button2.Enabled = true;
                MessageBox.Show("文件传输完毕!");
            }

接收端
 private void StartReceive()
            {
                int SendedCount = 0;
                int total = 0;
                int recv;
                byte[] datasize = new byte[4]; //用于接收文件大小
                byte[] receiveBytes = new byte[0]; //用于接收文件名
                //指向远程服务端节点
                EndPoint ipep = new IPEndPoint(IPAddress.Parse(this.textBox1.Text), int.Parse(this.textBox5.Text));
                IPEndPoint ipep1 = new IPEndPoint(IPAddress.Parse(this.textBox1.Text), int.Parse(this.textBox5.Text));
                //创建套接字
                Socket client = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
                UdpClient uu = new UdpClient(int.Parse(this.textBox5.Text));
                client.Bind(ipep1);
                receiveBytes = uu.Receive(ref ipep1);
                //获得[文件名]
                string SendFileName = System.Text.Encoding.Unicode.GetString(receiveBytes);         
                //创建一个新文件
                FileStream MyFileStream = new FileStream(SendFileName, FileMode.Create, FileAccess.Write);
                //已发送包的个数
               
                recv = client.ReceiveFrom(datasize,ref ipep);
                int size = BitConverter.ToInt32(datasize, 0);
                int dataleft = size;
                byte[] data1 = new byte[size];//用于接收文件
                while (total < size)
                {
                    recv = client.ReceiveFrom(data1,ref ipep);
                    if (recv == 0)
                    {
                        data1 = null;
                        break;
                    }
                    total += recv;
                    dataleft -= recv;
                }
                while (true)
                {
                    byte[] data = data1;
                    if (data.Length == 0)
                    {
                        break;
                    }
                    else
                    {
                        SendedCount++;
                        //将接收到的数据包写入到文件流对象
                        MyFileStream.Write(data, 0, data.Length);
                       
                    }
                }
            
                //关闭文件流
                MyFileStream.Close();
                //关闭套接字
                client.Close();
                this.button1.Enabled = true;
                MessageBox.Show("文件接收完毕!");
            }