.Crystal Report setdatasouce() giving Nullreferenceexception error

Question

Hello.

I am making a simple test report using Crystal Report with c#.

The report is loaded by a . ttx file;

On the controller I put:

 public ActionResult ObterRelatorio()
    {
        try
        {
            byte[] relatorio = new byte[] { };

            Response.AddHeader("Content-Disposition", string.Format("attachment; filename={0}.pdf","Relatorio"));

            List<QuestaoDTO> lista = QuestaoDTO.ObterRelatorio();
            RelatorioDeQuestao relatorioDeQuestao = new RelatorioDeQuestao();

            relatorio = relatorioDeQuestao.ObterRelatorio(lista);

            return File(relatorio, "application/pdf");
        }
        catch (Exception excecao)
        {
            TempData["MENSAGEM_ERRO"] = excecao.Message;

            return View();
        }
    }

In it I pass a list of objects.

When I load the report gives a Nullreferenceexception error on . Setdatasource(), even though the list is brought in the correct way.

public byte[] ObterRelatorio(IList<QuestaoDTO> listaDoRelatorioDTO)
    {
        try
        {
            Stream fluxoDeDadosDoRelatorio;
            int tamanhoDoFluxoDeDados;
            byte[] vetor;

            Relatorio.SetDataSource(listaDoRelatorioDTO);
            fluxoDeDadosDoRelatorio = Relatorio.ExportToStream(ExportFormatType.PortableDocFormat);
            tamanhoDoFluxoDeDados = Convert.ToInt32(fluxoDeDadosDoRelatorio.Length);
            vetor = new byte[tamanhoDoFluxoDeDados];
            fluxoDeDadosDoRelatorio.Read(vetor, 0, tamanhoDoFluxoDeDados);

            return vetor;
        }
        catch (NullReferenceException ex)
        {
            throw new NullReferenceException(ex.Message);
        }
        catch (Exception excecao)
        {
            throw new Exception(excecao.Message);
        }
    }

What can it be?

Editing, showing how he brings up the list: