Salesforce-Phonegap and Sencha touch integration issue

Question

I have developing an iOS app using Salesforce mobile SDK 1.4 with Sencha Touch for the front end. I am using Phonegap/Cordova version 2.2. My application is able to logon successfully with Salesforce. I can load app.js on the simulator smoothly but on a real device I am getting a WHITE BLANK SCREEN.

I am not getting any error at logs/console. I am using sencha touch version 2.1

This is my app.js

Ext.application({
name: 'Sencha',
controllers: ['Main'],
views: ['Main'],
stores: ['Contacts'],
models: ['Contact'],

launch: function() {
    Ext.Viewport.add({
        xtype: 'mainpanel'
    });
},                
});