Can't rotate camera view with my mouse with GvrViewerMain from GoogleVRSDK

Hi guys,

I downloaded Google VR SDK for Unity, I imported it to Unity and I used "GvrViewerMain" from Prefabs.
This prefab should give me working VR camera. But I can't rotate camera view by mouse (according tutorials it should work).
Do you know anybode how fix it?

Thank you.

I have Unity version 5.4.1f1.

Here is screenshot from my Unity (maybe can be useful)