Strange error on screen, debug does not show nda

InWebform,itisgivingsomeerror,thatwhendebugginginVisualStudio(f5)itdoesnotacknowledgeanyerror,howeverwhenitexitstheresultinthescreenwouldbelikeaninternalerror(500)ItdoesnothaveanyAJAXorsomethinglikethatisjusta'theoreticallysimple'page

Doubt:

Isthereanybetterwaytodebug?isthereanerrorthatdoesnotdisplaytheerroronthescreen?

web.config

<system.web><customErrorsmode="Off"/>

Basically I have a page wizard.aspx

otimizacao_pontos otim = new otimizacao_pontos();
otim .TotalPontos();
EntidadeWizard iPontos = new EntidadeWizard();
iPontos = (EntidadeWizard)Session["iPontos"];

class optimization_points

        public void TotalPontos()
        {
            EntidadeWizard iPontos = new EntidadeWizard();

/// monte de códigos 
HttpContext.Current.Session["iPontos"] = iPontos;

}

and the entity:

    public class EntidadeWizard
    {
        private int TotalImoveis = 0;

        public int TotalImoveis1
        {
            get { return TotalImoveis; }
            set { TotalImoveis = value; }
        }

        public int TotalImoveisFOTO { get; set; }
        public int TotalDestaque { get; set; }

        public double _E1_point { get; set; }
        public double _E2_point { get; set; }
        public double _E3_point { get; set; }
        public double _E4_point { get; set; }

        public double _E5_point { get; set; }
        public bool _E5_MailFull = false;
        public bool _E5_MailDomain = false;
        private bool _E5_Erro = false;

        public bool E5_Erro
        {
            get { return _E5_Erro; }
            set { _E5_Erro = value; }
        }

        public double _E6_point { get; set; }
        public bool _E6_Atualizado = false;

        public double _E7_point { get; set; }

        public double E7_point_Mega { get; set; }

        public double _E7_point_Mercado { get; set; }
        public double _E7_point_USA { get; set; }
        public double _E7_point_Trovit { get; set; }
        public double _E7_point_Ibiubi { get; set; }
        public double _E7_point_Fisgo { get; set; }
        public double _E7_point_Mitula { get; set; }
        public double _E7_point_Imohoo { get; set; }
        public double _E7_point_OLX { get; set; }
        public double _E7_point_Nuroa { get; set; }
        public double _E7_point_Divendo { get; set; }
        public double _E8_point { get; set; }
        private bool _E8_Correto = false;

        public bool E8_Correto
        {
            get { return _E8_Correto; }
            set { _E8_Correto = value; }
        }
        public double _E9_point { get; set; }
        public double _E9_percent { get; set; }
        public double _E10_point { get; set; }
        public double _E11_point { get; set; }
        public int _E11_Dias { get; set; }

        public double _E12_point { get; set; }
        public double _E12_percent { get; set; }

        public string _urlLogotipo { get; set; }


        private double _vTOTALInterno { get; set; }

        public double _vTOTAL
        {
            get { return _vTOTALInterno; }
            set { _vTOTALInterno = value; }
        }

        public string textMail { get; set; }

    }
}

Basically the class throws the values into the Session and then unboxing and retrieving the values, or should. I'm checking the entity if it has a bug..but I do not see it.