请教关于让控件label实现滚动字幕的效果问题

想让单元二中的label的caption属性调用单元一中的Edit中所输入的字符串，这样可以在label控件滚动的时候可以更改caption，实现如同滚动字幕的效果，我的代码可运行，但是label中总是无显示，显示不出Edit中所输入的字符。

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,unit2;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    TestStr:String;{ Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);

begin
  TestStr := Edit1.Text;
  form2.Show;

end;

end.

-----------------单元分隔----------------------

unit Unit2;

interface

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

type
  TForm2 = class(TForm)
    Timer1: TTimer;
    Label1: TLabel;
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    TestStr:String;
  end;

var
  Form2: TForm2;

implementation

uses Unit1;

{$R *.dfm}

procedure TForm2.Timer1Timer(Sender: TObject);


begin


  if label1.Left > -label1.Width then
    begin
    label1.Caption := TestStr;
    label1.Left := label1.left - 5;
    end
  else
    begin
    label1.Caption := TestStr;
    label1.Left := form2.Width - 35;
    end;


end;

end.