Ошибка: Exception class EAccessViolation with message 'Access violation at address 0045DE23'

unit Unit1;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, OleCtrls, SHDocVw, StdCtrls, Buttons;
 
type
  TForm1 = class(TForm)
    Edit1: TEdit;
    BitBtn1: TBitBtn;
    WebBrowser1: TWebBrowser;
    procedure BitBtn1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure WebBrowser1DownloadComplete(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
  adress: string;
  ********:string;
  html_tag: variant;
 
implementation
 
{$R *.dfm}
 
procedure TForm1.BitBtn1Click(Sender: TObject);
begin
if Edit1.Text<>'' then
adress:=Edit1.Text;
 
if Pos(********,adress)>0 then
WebBrowser1.Navigate(Edit1.Text);
 
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
WebBrowser1.Visible:=True;
********:='********.net/download';
end;
 
procedure TForm1.WebBrowser1DownloadComplete(Sender: TObject);
Var
  i: integer;
begin
html_tag:=webbrowser1.OleObject.Document.Forms.Item(0).Elements;
for i := 0 to (Html_tag.length-1) do
begin
if html_tag.Item(i).Name='submit_way_selection2' then
html_tag.Item(i).Click;
end;
end;
end.

WebBrowser1.Visible:=True