IdTCPServer回传给IdTCPClient字符串失败

Question

当服务端接收到客户端传来的字符串流后，返回一字符串给客户端以确认服务端已收到字符串流，但该确认的字符串服务端发不出去，何因？？代码如下：
客户端：
    IdTCPClient1.Connect;
    if (IdTCPClient1.ReadLn = 'OK') then
    begin
        Str := 'asdfasdfasd$%13123132112311313131###252345234!';
        AStream := TStringStream.Create(Str);
        IdTCPClient1.OpenWriteBuffer;
        IdTCPClient1.WriteStream(AStream);
        IdTCPClient1.CloseWriteBuffer;
        AStream.Free;
    end;
    Strs := IdTCPClient1.ReadLn;
    IdTCPClient1.Disconnect;服务端：
    AThread.Connection.WriteLn('OK');
    Astrem := TStringStream.Create('');
    AThread.Connection.ReadStream(Astrem, -1, True);
    Astrem.Seek(0, soFromBeginning);
    SStr := Astrem.DataString;
    Astrem.Free;
    Edit1.Text := SStr;
    AThread.Connection.WriteLn('Over');
    AThread.Connection.Disconnect;

Answer 1

服务端：
    AThread.Connection.WriteLn('OK');
    Astrem := TStringStream.Create('');
    AThread.Connection.ReadStream(Astrem, -1, True);
    Astrem.Seek(0, soFromBeginning);
    SStr := Astrem.DataString;
    Astrem.Free;
   //问题在这里把这行屏蔽掉可以了就  Edit1.Text := SStr;　 
    AThread.Connection.WriteLn('Over');
    AThread.Connection.Disconnect;
  原因学习中

Answer 2

IdTCPServer是多线程的， Edit1不是。