Build Android show nothing

Unity Engine
1

Hi, i am beginner on Unity. I try to use unity 4.6 UI system. I just create a new scene. Change the main camera to orthographics mode. Create a Canvas. Add a button. Change the Canvas Render mode to Screen space -Camera. Then i build an android apk. It cannot show button. Any setting i miss??

Thanks.

2

did you set the camera to the canvas? (although that shouldnt matter want to see if that a bug or not)

3

Have you tried building one of the provided scenes to see how it looks?