Error (401) Unauthorized, when consuming WSDL service

I am trying to consume a service that is done in PHP from a Windows Forms application, but I get this error:

Error image capture:

This is the code:

private void btn_getBalance_Click(object sender, EventArgs e)  
{
    try
    {
        if (!ValidarCredenciales()) { return; }

        txtResultadosConsultas.Text = String.Empty;

        wspagos _solicitaSaldo = new wspagos();
        _solicitaSaldo.GetBalanceCompleted += PideSaldo_GetBalanceCompleted;
        _solicitaSaldo.Credentials = new NetworkCredential(Credenciales.userName, Credenciales.password, Credenciales.hostName);

        ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(ValidarCertificado);

        _solicitaSaldo.GetBalanceAsync(ConfiguracionWSMetrotel.userName, ConfiguracionWSMetrotel.password,
                                        ConfiguracionWSMetrotel.company, ConfiguracionWSMetrotel.terminal,
                                        Convert.ToInt32(txtTelefono.Text), ConfiguracionWSMetrotel.tipo);

    }
    catch (Exception ex)
    { throw ex; }
}