请教delphi7.0中的TcpServer的onAccept事件的用法，多谢指点！分数不够再加！

请问delphi7.0中的tcpServer的onaccept事件什么时候触发，我下面的这个程序，发送了两次数据，但是只触发了一次，为什么啊？
procedure TForm1.Button1Click(Sender: TObject);
var Temp:Tbitmap;
    TempJpg:TJpegimage;
    imgSize,s:String;
begin
  if OpenPictureDialog1.Execute then
  begin
    Temp:=TBitmap.Create;
    TempJpg:=TJpegimage.Create;
    try
      Temp.LoadFromFile(OpenpictureDialog1.FileName);
      Tempjpg.Assign(Temp);
      Tempjpg.CompressionQuality:=10; //压缩率
      Tempjpg.SaveToStream(imgStreamSent);
     finally
      Temp.Free;
    end;
  end;
  TcpClient1.RemoteHost:=edtRemoteHost.Text;
  TcpClient1.RemotePort:=edtRemotePort.Text;
  if edtRemotePort.Text <>edtLocalport.Text then
  showmessage('端口不匹配');
  if TcpClient1.Connect then
  begin      //Tempjpg.Free;
      imgStreamSent.Position:=0;
      imgSize:=intToStr(imgStreamSent.Size);
      TcpClient1.Sendln(imgSize); //第一次发送
      //等待通知传送
      s:=TcpClient1.Receiveln;
      while not (s = 'Ready for Image' ) do
      s:=TcpClient1.Receiveln;      TcpClient1.Sendln('haha');  //第二次发送      //imgStreamSent.Position:=0;
      //TcpClient1.SendStream(imgStreamSent);
      //TcpClient1.Disconnect;  end;
end;procedure TForm1.TcpServer1Accept(Sender: TObject;
  ClientSocket: TCustomIpClient);
var Tempimg:TBitmap;
    Tempjpg:TJpegimage;
    s:String;
    OneFrameSize:Integer;
    RevBuffer:array[1..1024] of byte;
begin
  //accept事件是什么触发的？
  s:=ClientSocket.Receiveln;
  if Revimg=false then
  begin    RevSize:=StrToInt(s);
    while (RevSize=0) do
    RevSize:=StrToInt(ClientSocket.Receiveln);
    Revimg:=true;
    ClientSocket.Sendln('Ready for Image');
  end else
  begin
    ……
    Revimg:=false;
  end;
end;