Please read my more complete answer to the more recent (and complete) question. The link is below:
ANDROID webdriver with selenium
I've left the following answer just in case it's also useful...
Neha,
first things first, have you read the relevant wiki page for Android driver on the Selenium project? http://code.google.com/p/selenium/wiki/AndroidDriver
As it says, the last version of Android WebDriver to support Android 2.2 is release 2.16 of the APK, http://code.google.com/p/selenium/downloads/detail?name=android-server-2.16.apk
If you would prefer to use the current versions of the Android driver I would recommend you try using newer versions of Android e.g. 2.3 as a minimum. As you may know, it's easy to create a new emulator, a new AVD as they're also known, that has 2.3
If you're still stuck once you've either tried using 2.16 of Android-WebDriver in your 2.2 emulator, or the current version of Android-WebDriver in an emulator with 2.3 or later of Android, perhaps you could add the stack trace and the complete Java source for your code online here. That'd help people to help you :)
Good luck
Julian.