我的idTcpClient收到的数据是混乱的数据。麻烦各位富翁来看一看(200分)

T_PPTP_HEAD_tag = packed record
    Version: LongWord; 
    P_Type: LongWord; 
    Total_Length: LongWord; 
    Command_ID: LongWord; 
    Sequence_ID: LongWord;
end;//the packet head record

T_empty=record
end;//empty record

T_PPTP_Connect_tag = TEmpty; //the connect packet body is Empty

T_PPTP_Connect_REP_tag = TEmpty;//the connect reply packet body is empty too,

T_PPTP_Connect=packed record
    head:T_PPTP_Head_tag;
    body:T_PPTP_Connect_tag;
end;//the connect packet

T_PPTP_Connect_REP=packed record
    head:T_PPTP_head_tag;
    body:T_PPTP_Connect_REP_tag;
end;//the connect reply packet

var
  pkt: T_PPTP_Connect;
  pktREP: T_PPTP_Connect_REP;
begin
    AThread.Connection.ReadBuffer(pkt, sizeof(pkt));
    if pkt.head.Command_ID = PPTP_Connect then //PPTP_connect is a integer number in my protocol,like PPTP_Connect_REP
        begin
         pktREp:=createPPTP_Connect_REP();//a function to create a pptp_connect_rep packet .just fill the command_id.
         AThread.Connection.WriteBuffer(pktREP, sizeof(pktREP));
        //Showmessage('a client connected!');
       end;
end;

var
  Adata: TmemoryStream;
  iCmd: integer;
  Head: T_PPTP_Head_tag;
  pktConnectREP:T_PPTP_Connect_REP;
begin
    while AThread.Connection.Connected do
    begin
      Adata := TmemoryStream.Create;
      try
        Adata.Clear;
        Adata.Position := 0;
        AThread.Connection.ReadStream(Adata, -1, false);
        Adata.Position := 0;
        Adata.Read(Head, sizeof(head));//I have many packets in my protocol,so I can't readbuffer..
        iCmd := Head.Command_ID;//Get the command_id
        Adata.Position := 0;
        if iCmd=PPTP_Connect then//PPTP_connect is a integer number in my protocol,like PPTP_Connect_REP
            begin
                pktConnectREP:=createPPTP_Connect_REP();
                AThread.Connection.WriteBuffer(pktConnectREP, sizeof(pktConnectREP), false);
            end;
      finally
        Adata.Free;
      end;
    end;    
end;

var
pktConnect:T_PPTP_Connect;
begin
      TcpClient.Connect();
      pktConnect := createPPTP_Connect;//create a packet the command_id is PPTP_Connect;
      TcpClient.WriteBuffer(pktConnect, sizeof(pktConnect));
      TcpClient.ReadBuffer(pktConnectREP, sizeof(pktConnectREP));
      if pktConnectREp.head.Command_ID = PPTP_Connect_REP then
       Showmessage('Receive Connect REp packet');//////////////////the data is True, I can get the reply and I can 
                                                 //////////////////know the connection is established and OK.
end;

var
  pktConnect, pktTemp: T_PPTP_Connect;
  pktConnectREP: T_PPTP_CONNECT_REP;
  Adata: TmemoryStream;
  Head: T_PPTP_HEAD_tag;
  iCmd: LongWord;
begin
  if not TCPClient.Connected then exit;//if not connected then exit;

  pktConnect := createPPTP_Connect();//create a pptp_connect packet...and the command_id is PPTP_Connect
  Adata := TmemoryStream.Create;
  try
    try
      Adata.Position := 0;
      Adata.Write(pktConnect, sizeof(pktConnect));
      Adata.Position := 0;
      TcpClient.WriteStream(Adata, true, true, 0);//write the packet ,
      Adata.Position := 0;
      ////////////////////////////////////////
      TCPClient.ReadStream(Adata, -1, false);     //////Read a stream....or Readbuffer ...both methods didn't work well.
//      tcpClient.ReadBuffer(Head, sizeof(Head));///////////but receive not a packet ,I'm sure that the server send a PPTP_Connect_REP packet but client didn't receive it correctly....

      Adata.Position := 0;
      Adata.Read(Head, sizeof(head));
      iCmd := Head.Command_ID;
      Adata.Position := 0;
      ShowMessage(format('Protocol:%s%sVersion:%d%sP_Type:%d%sTotal_length:%d%sCommand_id:%d%ssequence_id:%d',
        [ResultCommandString(iCmd), Char(13), Head.Version, Char(13), Head.P_Type, Char(13), Head.Total_Length, Char(13), Head.Command_ID, Char(13), Head.Sequence_ID]));//the message is not correct........I 'm puzzled......Help!!!
    except
      on e: exception do
      begin
        Showmessage('OnExecute Exception: [' + E.ClassName + ']: ' + E.Message);
      end;
    end;
  finally
    Adata.Free;
  end;
end;    
end;