IOS 4.0 code not running on IOS 4.2

I wrote a code on IOS SDK 4.0 and tried running on a device which contains IOS 4.2. I am seeing a empty navigation view. What changes in my code I should do to run it on开发者_StackOverflow the target version of SDK.

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It's very hard to say without having more information on the project and what technologies within iOS it makes use of. Is there anything in the release notes that sheds light on your problem:

http://developer.apple.com/library/ios/#releasenotes/General/RN-iOSSDK-4_2/

Might be worth checking 4.1 ones as well:

http://developer.apple.com/library/ios/#releasenotes/General/RN-iPhoneSDK-4_1/