使用现有视图控制器的ipad拆分视图

I have a storyboard - a tableview leading to a detail view - and the layout works for iPhone. I now want to create a separate storyboard for iPad which is a split view showing the same table as iPhone on the left (master) and same detail on the right. I have tried: adding a new storyboard, dragging a splitview, making rootVC class for master and detailVC class for detail, turning app to universal, placing iPad storyboard name in box. Also, the same named outlets are connected. But when I run the screen is black. What am I missing? I have a storyboard - a tableview leading to a