实现顺序播放两个avi文件，用一个线程判断播放器播放完一个,再播另一个

不知道为什么不行?希望大虾指点下 谢谢
代码:
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, MPlayer, StdCtrls, ExtCtrls;type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    MediaPlayer1: TMediaPlayer;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
    procedure playvedio(filename:string);
  end;  TplayerThread = class(TThread)
  private
    { Private declarations }
  protected
    procedure Execute; override;
  public  end;var
  Form1: TForm1;
  fname1,fname2:string;implementation
{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
begin
     TplayerThread.Create(false);
     playvedio(fname1);
end;
{ TplayerThread }procedure TplayerThread.Execute;
begin
  freeonterminate:= true;
  if form1.MediaPlayer1.Mode= mpStopped then
   form1.playvedio(fname2);
end;procedure TForm1.playvedio(filename: string);
begin
     mediaplayer1.FileName:= filename;
     mediaplayer1.Display:= panel1;
     mediaplayer1.Open;
     mediaplayer1.DisplayRect:= Rect(0,0,panel1.Width,panel1.Height);
     mediaplayer1.Play;
end;procedure TForm1.FormCreate(Sender: TObject);
begin
     fname1:= 'F:\avi\SISINFO.avi';
     fname2:= 'F:\avi\SISTVLCD.AVI';
end;end.