Hi Sukumarsb,
We can't answer every specific code issue that is posted to this forum. Instead, our stance is to provide a general, code-free solution and that is qRules v2.3. qRules v2.3 has great support for mapping to lists and it even round trips and supports reconciling edits made on the SharePoint list when you reopen the XML form. qRules helps us defray the cost of this forum, and it's really cheap. A free trial is all you need to prototype your solution. We also provide discount for people who send us a 2-3 sentence testimonial. That makes it close to free. Given how much time it will save you, it's worth much more than that.
If you want to pay for support to debug your code, we provide low-cost InfoPath 911 support options on Qdabra.com's web site. Just click on Support.
Best of luck,