两个id udpserver 一个收到信息做处理后如何返回给发送端?有代码

//发送端
procedure TForm1.btn1Click(Sender: TObject);
begin
clear;
MyRecord.Command:=1;
strcat(MyRecord.UserName,PChar(edt1.Text));
strcat(MyRecord.PassWord,PChar(edt2.Text));
idpsrvr1.SendBuffer('localhost',8800,MyRecord,SizeOf(MyRecord));
end;
//发送端接收事件
procedure TForm1.idpsrvr1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
  var
  str:string;
begin
   AData.Read(str,AData.Size); //收不到服务器返回的信息;
   ShowMessage(str);
end;接收端
procedure TForm1.idpsrvr1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
  var
  funcstr:string;
begin
  AData.ReadBuffer(MyRecord,AData.Size);
  if MyRecord.Command=1 then //注册
  begin
   funcstr:=userreg(MyRecord.UserName,MyRecord.PassWord);
   ShowMessage(funcstr);//注册成功了
   ABinding.Send(funcstr,sizeof(funcstr),0);//返回给发送端?上边的收不到
  end;end;
帮忙看下 谢谢.