Facebook window not showing correctly & cancel button is invisible in iphone

I am integrating facebook login functionality in my iphone application. When I click on "Login with Facebook" button then facebook window opens which is shown below

As you see , "Facebook" is part开发者_开发百科ially visible. Also I can not see any "Cancel" button on the screen. I can not figure out what is wrong with this. By the way I am using official facebook ios sdk from GitHub. My ios sdk is 4.3 & xcode 4. I want "Cancel" buuton on this scrren so that user can navigate back to application & also facebook Title on the view should be displayed correctly. Please guide me. Thanks.