NetworkStream of TcpClient does not receive each package

I have a part of code about Send and Receive use Network stream. I send two packages thought socket but Receive method receive one package and it contains two packages . I don't know why. help me please.

private void ClientReceive()
    {
        try
        {
            DataPackage pakage = null;
            byte[] buffer = null;
            byte[] temp = null;
            int receivebytes = 0;
            while (true)
            {
                Thread.Sleep(500);
                buffer = new byte[1024];
                receivebytes = this.m_stream.Read(buffer, 0, buffer.Length); //bug only receive one package but it contains 2 package, which is sent via "Send" method
                this.m_stream.Flush();
                if (receivebytes == 0)
                {
                    this.IsExit = true;
                    if (this.OnClientExit != null)
                    {
                        this.OnClientExit(this, new ClientExitAvgs(this.ClientInfo, ShutdownType.Shutdown));
                    }
                    this.StopClient();
                    break;
                }
                temp = new byte[receivebytes];
                Array.Copy(buffer, temp, receivebytes);
                pakage = new DataPackage();
                pakage.DataHeader(temp);
                switch (pakage.Cmd)
                { 
                    case Command.Shutdown:  // client shutdown or application close
                        buffer = new byte[4];
                        this.m_stream.Read(buffer, 0, buffer.Length);
                        this.m_stream.Flush();
                        ShutdownType downType = (ShutdownType)BitConverter.ToInt32(buffer, 0);
                        if (OnClientExit != null)
                        {
                            OnClientExit(this, new ClientExitAvgs(this.ClientInfo, downType));
                        }
                        break;
                    case Command.Name:
                        buffer = new byte[pakage.DataLength];
                        this.m_stream.Read(buffer, 0, buffer.Length);
                        this.m_stream.Flush();
                        string regex = Encoding.Unicode.GetString(buffer);
                        this.ClientInfo = ComputerInfo.GetComputerInfo(regex);
                        this.IsReceiveClientInfo = true;
                        break;
                    case Command.USB:
                        buffer = new byte[4];
                        this.m_stream.Read(buffer, 0, 4);
                        this.m_stream.Flush();
                        UsbType type = (UsbType)BitConverter.ToInt32(buffer, 0);
                        UsbAvgs e = new UsbAvgs();
                        e.ClientInfo = this.ClientInfo;
                        e.Usbtype = type;
                        switch (type)
                        {                                
                            case UsbType.NotRegister:       //connected and not register

                                break;
                            case UsbType.Registered:            // register for usb device
                                break;
                            case UsbType.Remove:                // usb device removed
                                break;
                            case UsbType.Connected:         // usb device connected and registered
                                break;
                        }
                        if (this.OnUsbExecute != null)
                        {
                            this.OnUsbExecute(this, e);
                        }
                        break;
                }
            }
        }
        catch
        {

        }
    }

Send method. I sent 2 package but receive method receive one.

private void ClientSend()
    {
        try
        {
            DataPackage pakage = null;
            byte[] buffer = null;
            while (true)
            {
                Thread.Sleep(500);
                while (this.SendQueue.Count > 0)
                {
                    pakage = new DataPackage();
                    pakage = (DataPackage)this.SendQueue.Dequeue();
                    //send command
                    buffer = package.ToBytesHeader();
                    this.m_stream.Write(buffer, 0, buffer.Length);
                    this.m_stream.Flush(); // send first package
                    //Thread.Sleep(10);
                    switch (pakage.Cmd)
                    {
                        case Command.Name:
                            //send computer name
                            buffer = Encoding.Unicode.GetBytes(ComputerInfo.Regex());
                            this.m_stream.Write(buffer, 0, buffer.Length); //send second package
                            this.m_stream.Flush();
                            break;
                        case Command.USB:
                            while (this.SendQueue.Count == 0) { }
                            UsbType type = (UsbType)this.SendQueue.Dequeue();
                            buffer = null;
                            buffer = BitConverter.GetBytes((int)type);
                            this.m_stream.Write(buffer, 0, buffer.Length);
                            this.m_stream.Flush();
                            break;
                        case Command.Shutdown:
                            while (this.SendQueue.Count == 0) { }
                            buffer = BitConverter.GetBytes((int)(ShutdownType)this.SendQueue.Dequeue());
                            this.m_stream.Write(buffer, 0, buffer.Length);
                            this.m_stream.Flush();
                            break;
                    }
                }
            }
        }
        catch
        {

        }
    }