Почему не связываются 2 формы..?

[manchester_alan]

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

uses Unit2;

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
var i:Integer;
begin
 case ComboBox1.ItemIndex of
  0:
  begin
  for i:=0 to listbox1.
  end;
  1:
  begin

  end;
  2:
  begin

  end;
  3:
  begin

  end;
  end;
end;

end.

вот одна форма..

unit Unit2;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Unit1;

type
  TForm2 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    ListBox1: TListBox;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Edit1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;
  var textchange:Boolean;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
begin
if textchange=true then
    begin
    ListBox1.Items.Add(Edit1.Text);
     Edit1.Text:='';
     textchange:=false;
    end;
end;

 procedure TForm2.Button2Click(Sender: TObject);
begin
Form1.Show;
end;

procedure TForm2.Edit1Change(Sender: TObject);
begin
 textchange:=true;
end;

end.

вот вторая...

Как их связать?

[newerow1989]

Во 2-м юните

implementation

uses Unit1;