UITableView is displayed half of the screen after converting to Universal app

I want to convert an iphone app to universal. the iphone storyboard has a UITableView. I used Auto-layout and Use Size Classes using the latest XCode and added missing constraints however I cannot make the tableView and its cells go all the way down; it's only half way of the screen. Can anyone have an idea on how to do this; Thank you very much. I attached the screenshot here View Screenshot

via Chebli Mohamed