Erreur delphi- javascript

Ce code la marche sur mon poste.
Une fiche, un bouton, un webBrowser
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unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, OleCtrls, SHDocVw, StdCtrls, MSHTML_TLB ;
 
type
  TForm1 = class(TForm)
    Button1: TButton;
    WebBrowser1: TWebBrowser;
    procedure FormActivate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
  private
    { Déclarations privées }
  public
    { Déclarations publiques }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
procedure javascript (doc: IHTMLDocument2 ; script: string);
begin
   if doc <> nil then
   begin
     if doc.parentWindow <> nil then
       doc.parentWindow.ExecScript(script, Olevariant('javascript')) ;
   end;
end;
 
 
procedure TForm1.FormActivate(Sender: TObject);
begin
  WebBrowser1.Navigate('http:\\www.google.fr');
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
  document: IHTMLDocument2;
begin
  document := WebBrowser1.Document as IHTMLDocument2;
  javascript (document,'alert (''OK'')') ;
end;
 
end.