Saber si hay un disco dentro del lector de CD/DVD

[REHome]

Lo he intentado ahcer pero nome sale.

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
function DiskInDrive(Drive: Char): Boolean;
  // Disk can be a floppy, CD-ROM,...

var
  Form1: TForm1;
  ErrorMode: Word;

  begin
  { make it upper case }
  if Drive in ['a'..'z'] then Dec(Drive, $20);
  { make sure it's a letter }
  if not (Drive in ['A'..'Z']) then
    raise EConvertError.Create('Not a valid drive ID');
  { turn off critical errors }
  ErrorMode := SetErrorMode(SEM_FailCriticalErrors);
  try
    { drive 1 = a, 2 = b, 3 = c, etc. }
    if DiskSize(Ord(Drive) - $40) = -1 then
      Result := False
    else
      Result := True;
  finally
    { Restore old error mode }
    SetErrorMode(ErrorMode);
  end;
end;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
if DiskInDrive('a') = False then
    ShowMessage('Drive not ready');
end;

end.