怎样给TMainMenu添加mousemove事件？

我自己想给TMainMenu加一个mousemove事件，如下:
unit Menu;

interface

uses

Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
Shellapi, StdCtrls, ExtCtrls, Menus;

type
TMenu = class(TMainMenu)

private
{ Private declarations }
FOnMouseMove: TNotifyEvent;
procedure FSetOnMouseMove(value: TNotifyEvent);

protected
{ Protected declarations }
procedure wmmousemove(var Msg: TMessage); message WM_MOUSEMOVE;

public
{ Public declarations }
constructor Create(AOwner: TComponent); override;
destructor Destroy; override;

published
{ Published declarations }
property OnMouseMove: TNotifyEvent read FOnMouseMove write FSetOnMouseMove;

end;

implementation

procedure Register;
begin
RegisterComponents('Samples', [TMenu]);
end;

{ TMenu }

procedure TMenu.wmmousemove(var Msg: TMessage);
begin
if Assigned(FOnMouseMove) then
FOnMouseMove(Self);
end;

constructor TMenu.Create(AOwner: TComponent);
begin
inherited;

end;

destructor TMenu.Destroy;
begin

inherited;
end;

procedure TMenu.FSetOnMouseMove(value: TNotifyEvent);
begin
if @FOnMouseMove <> @value then
FOnMouseMove := Value;
end;

end.


但用install component居然不让install！？（就是install那个按钮是灰的）是哪个地方写错了吗？以前没做过这种东西。