Camera.RenderToCubemap draws nothing on iOS

Hi all

I want to implement realtime reflection on iOS. I use Camera.RenderToCubemap to draw the scene into a cube render texture and everything works fine in editor. But when I upload the project to iOS device, the reflection disappears and the scene is a little blue, looks like the clear color. The call returns true and my device is iPad Air.

I have tried to use static cube map, it was fine. So the shaders are ok, is there anyone succeed using Camera.RenderToCubemap on iOS? Is that a bug? I'm using 4.5.4 pro

 

The documentation says followring intersting thing

You may have a debug log tell you if it works on your device or not.

 

iPad Air supports it, the problem looks like something about shader initialization. Actually, I call Camera.RenderToCubemap only once at the very beginning. If I do this after the first frame, the scene can be drawn perfectly.