How to properly setup redis for session store

I am trying to setup Redis Store like this:

var express = require('express');
var app = express();
.......
.......
var session = require('express-session');
var redis = require("redis").createClient();
var RedisStore = require("connect-redis")(session);

app.use(session({
  store: new RedisStore({
     host: 'localhost',
     port: 6379,
     client: redis
   }),
  secret: 'keyboard cat'
}));

But using like this the passport.js wont work and the express-flash will throw an error: `Error: req.flash() requires sessions.

I believe Redis is not working at all.

I am very confuse with the configuration also, should i put localhost in the host key? I am using Cloud 9, not my localhost.

What i am doing wrong?