IdTCPClient传输文件出错

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdBaseComponent, IdComponent, IdTCPConnection,
  IdTCPClient, ComCtrls;type
  TForm1 = class(TForm)
    OpenDialog1: TOpenDialog;
    IdTCPClient1: TIdTCPClient;
    Button1: TButton;
    edtFileName: TEdit;
    edtAddress: TEdit;
    Button2: TButton;
    ProgressBar1: TProgressBar;
    StatusBar1: TStatusBar;
    Label2: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
begin
    OpenDialog1.Execute;
   edtFileName.Text:=OpenDialog1.FileName
end;procedure TForm1.Button2Click(Sender: TObject);
var
    iFileHandle:integer;
    iFileLen,cnt:integer;
    buf:array[0..4096] of byte;
begin
if (edtAddress.Text<>'')and (edtFileName.Text<>'') then
begin
    IdTCPClient1.Host:=edtAddress.Text;
    IdTCPClient1.Port:=9925;
    try
      IdTCPClient1.Connect(5000);
    except
      StatusBar1.Panels[0].Text:='连接接受方失败!';
      exit;
    end;
    if IdTCPClient1.Connected then
    begin
      iFileHandle:=FileOpen(edtFileName.Text,fmOpenRead);
      iFileLen:=FileSeek(iFileHandle,0,2);
      FileSeek(iFileHandle,0,0);
      ProgressBar1.Max:=iFileLen;
      ProgressBar1.Position := 0;
      IdTCPClient1.WriteLn(ExtractFileName(edtFileName.Text)+'|'+IntToStr(iFileLen));
      while true do
      begin
        Application.ProcessMessages;
        cnt:=FileRead(iFileHandle,buf,4096);
        IdTCPClient1.WriteBuffer(buf,cnt);
        IdTCPClient1.WriteInteger(cnt);
        ProgressBar1.Position:=ProgressBar1.Position + cnt;
        StatusBar1.Panels[0].Text:='正在传送文件...';
        if cnt<4096 then
            break;
      end;
      FileClose(iFileHandle);
      Label2.Caption:='文件传送完成!';
      StatusBar1.Panels[0].Text:='文件传送完成!';
     end;
end
else
    ShowMessage('请选择要传送的文件和或接受方地址');end;end.错误：list index out of bounds(0)