session.socket.io throws: "Error: could not look up session by key: jsessionid"

I have two servers:

1. Webserver: 127.0.0.1:3000
2. socket.io server: 127.0.0.1:4000

I'm trying to read the session using "session.socket.io" module from the socket.io server. But I get:

"Error: could not look up session by key: jsessionid"

Webserver code:

// Session
var session = require('express-session');
var RedisStore = require('connect-redis')(session);
app.use(session({store: new RedisStore(), key:'jsessionid', secret:credentials.cookieSecret}));
app.use(require('cookie-parser')(credentials.cookieSecret));

socket.io Server:

// Cookie
var cookieParser = require('cookie-parser');
app.use(cookieParser(credentials.cookieSecret));

// Session
var session = require('express-session');
var RedisStore = require('connect-redis')(session)
    , redisStore = new RedisStore();
app.use(session({store: redisStore , key:'jsessionid', secret:credentials.cookieSecret}));

var SessionSockets = require('session.socket.io')
  , sessionSockets = new SessionSockets(io, redisStore , cookieParser(), 'jsessionid'); 

sessionSockets.on('connection', function(err, socket, session) {

    console.log('connection event occured');
    console.log("session is: " + session);
    console.log("error is: " + err);
});

Why is it happening?