Error using Redis on node.js

Hello, I am trying to use REDIS in an application node to control sections, however, when I use I get the error:

Error: req.flash() requires sessions
   at Error (native)
   at IncomingMessage._flash [as flash]..................

Follow my APP code:

var express = require('express');
var path = require('path');
var favicon = require('serve-favicon');
var logger = require('morgan');
var cookieParser = require('cookie-parser');
var bodyParser = require('body-parser');
var load = require('express-load');
var methodOverride = require('method-override');
var expressSession = require('express-session');
var flash = require('express-flash');
var auth = require('./app/middleware/auth');


var redisStore = require('connect-redis')(expressSession);
var store = new redisStore();

var app = express();

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'ejs');

// uncomment after placing your favicon in /public
//app.use(favicon(path.join(__dirname, 'public', 'favicon.ico')));
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: false }));

app.use(methodOverride('_method'));
app.use(expressSession({secret: 'node_essencial', resave: true, saveUninitialized: false, store: store}));

app.use(flash());

app.use(cookieParser());
app.use(express.static(path.join(__dirname, 'public')));

app.all('/admin/*', auth);
app.all('/sup/*', auth);


load('models', {cwd: 'app'})
  .then('controllers')
  .then('routes')
  .into(app);

// catch 404 and forward to error handler
app.use(function(req, res, next) {
  var err = new Error('Not Found');
  err.status = 404;
  next(err);
});

// error handler
app.use(function(err, req, res, next) {
  // set locals, only providing error in development
  res.locals.message = err.message;
  res.locals.error = req.app.get('env') === 'development' ? err : {};

  // render the error page
  res.status(err.status || 500);
  res.render('error');
});

module.exports = app;