Managing persistence sessions in NodeJS

i'm trying to set up a very basic session manager. So, first i came with this code:

 var session     = require('express-session');
 var MongoStore   = require('connect-mongo')(session);

// define session store
app.use(session({
    secret: 'meh',
    saveUninitialized: true,
    resave: true,
    store: new MongoStore({
       db : 'express'
    })
}));

My current setup is nodejs/express4 with all modules installed locally. now, how can i share this app without having problems with connect-mongo? because, if i run it on other machine, i get this error:

 "error connection to database:failed to connect to [127.0.0.1:27017]..."

Do you know what may be wrong ?