Problema com código

unit UTabela;

interface

uses
  UCollection, Classes;

type
  TTabela = class
  private
    FCampos: TCampos;
  public
    constructor Create;
    property CamposTab: TCampos read FCampos write FCampos;
  end;

var
  FTabela: TTabela;

implementation

uses SysUtils;

{ TTabela }

constructor TTabela.Create;
begin
  inherited Create;
  FCampos := TCampos.Create(TCollectionItem);
end;

initialization
  if FTabela = nil then
    FTabela := TTabela.Create;

  //TTabela.Create;

finalization
  FreeAndNil(FTabela);

end.

unit URegistradas;

interface

uses
  UTabela, UCollection, Classes, SysUtils, Dialogs;

type
  TMercadoria = class(TTabela)
  public
    constructor Create;
  end;

var
  CampoTab: TCampo;

implementation

{ TMercadoria }

constructor TMercadoria.Create;
begin
  inherited Create;
  CampoTab := CamposTab.Add;
  CampoTab.Nome := ´Teste´;
  ShowMessage(IntToStr(CamposTab.Count));
end;


initialization
  if CampoTab = nil then
    CampoTab := TCampo.Create(nil);


finalization


end.

unit UCollection;

interface

uses
  Classes, SysUtils;

type
  TCampo = class(TCollectionItem)
  private
    FNome: string;
  public
    property Nome: string read FNome write FNome;
  end;

  TCampos = class(TCollection)
  private
    function GetItems(Index: Integer): TCampo;
  public
    function Add: TCampo;
    property Items[index: Integer]: TCampo read GetItems;
  end;

var
  Campo: TCampo;
  Campos: TCampos;

implementation

uses TypInfo;

function TCampos.GetItems(index: Integer): TCampo;
begin
  Result := TCampo(inherited GetItem(Index));
end;

function TCampos.Add: TCampo;
begin
  Result := TCampo(inherited Add);
end;

initialization
  if Campo = nil then
    Campo := TCampo.Create(nil);

  if Campos = nil then
    Campos := TCampos.Create(TCampo);

finalization
  FreeAndNil(Campo);
  FreeAndNil(Campos);

end.

  Campo := FTabela.CamposTab.Add;
  Campo.Nome := ´Teste´;
  ShowMessage(IntToStr(Campos.Count));