Hi Raja Gopal,
Thank you for getting back to us.
Using the information provided we are not able to determine what might be causing this exception by your side.
For the time being I may suggest you to take a look at the following list of exceptions and proposed resolutions here.
Check out Telerik Analytics, the service which allows developers to discover app usage patterns, analyze user data, log exceptions, solve problems and profile application performance at run time. Watch the videos
and start improving your app based on facts, not hunches.