почему выводит ошибку

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, ComCtrls, OleCtrls, SHDocVw;

type
TForm1 = class(TForm)
btn1: TButton;
btn2: TButton;
btn3: TButton;
btn4: TButton;
edt1: TEdit;
pb1: TProgressBar;
wb1: TWebBrowser;
procedure btn1Click(Sender: TObject);
procedure btn2Click(Sender: TObject);
procedure btn3Click(Sender: TObject);
procedure btn4Click(Sender: TObject);
procedure FormCreate(Sender: TObject);
procedure wb1ProgressChange(Sender: TObject; Progress,
ProgressMax: Integer);
procedure wb1StatusTextChange(Sender: TObject; const Text: WideString);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btn1Click(Sender: TObject);
begin
WebBrowser1.GoBack;
end;

procedure TForm1.btn2Click(Sender: TObject);
begin
WebBrowser1.GoForward;
end;

procedure TForm1.btn3Click(Sender: TObject);
begin
WebBrowser1.GoHome;
end;

procedure TForm1.btn4Click(Sender: TObject);
begin
WebBrowser1.Navigate(Edit1, Text);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
WebBrowser1.Navigate('Gogle.com');
end;

procedure TForm1.wb1ProgressChange(Sender: TObject; Progress,
ProgressMax: Integer);
begin
ProgressBar1.Max:= ProgressMax;
ProgressBar1.Position:=Progress;
end;

procedure TForm1.wb1StatusTextChange(Sender: TObject;
const Text: WideString);
begin
StatusBar1.SimoleText:=Text;
end;

end.

Вот ошибка:
[Error] Unit1.pas(41): Undeclared identifier: 'WebBrowser1'
[Error] Unit1.pas(41): Missing operator or semicolon
[Error] Unit1.pas(46): Undeclared identifier: 'WebBrowser1'
[Error] Unit1.pas(46): Missing operator or semicolon
[Error] Unit1.pas(51): Undeclared identifier: 'WebBrowser1'
[Error] Unit1.pas(51): Missing operator or semicolon
[Error] Unit1.pas(56): Undeclared identifier: 'WebBrowser1'
[Error] Unit1.pas(56): Missing operator or semicolon
[Error] Unit1.pas(61): Undeclared identifier: 'WebBrowser1'
[Error] Unit1.pas(61): Missing operator or semicolon
[Error] Unit1.pas(67): Undeclared identifier: 'ProgressBar1'
[Error] Unit1.pas(67): Missing operator or semicolon
[Error] Unit1.pas(68): Missing operator or semicolon
[Error] Unit1.pas(68): Incompatible types: 'TPosition' and 'Integer'
[Error] Unit1.pas(74): Undeclared identifier: 'StatusBar1'
[Error] Unit1.pas(74): Missing operator or semicolon
[Fatal Error] Project1.dpr(5): Could not compile used unit 'Unit1.pas'