NEDB is clearing content of file when app's relauched

I have written NodeWebKitApp in which I saving user's data (like name, uid and settings for later use). I can insert document fine and I can see the content (file size is about 2 KB).

But, if close app and re-open app after closing, saved is lost and I see 0 bytes file size.

On debugging, I found that this happens when this line is executed: db = new Datastore({ filename: myPath, autoload: true });

I tried to debug nedb/persistance.js but could not get any success. I also tried loading d/b manually by calling loadDatabase(function(err) {}) but not success.

Here is snippet of code:

var Datastore = require('nedb'),  

.. .. ..

myPath = "/.myApp/user.db", db = new Datastore({ filename: myPath, autoload: true });