Which version of the Gear VR hardware do you have and which phone model are you trying to use?
Some versions of the Gear VR hardware only work with specific phone models.
There have been 4 iterations of the Gear VR hardware released (so far).
The following website shows how to distinguish the hardware and which phones work with the hardware
http://www.roadtovr.com/everything-y...compatibility/
R320 Gear VR works with
* Samsung Galaxy Note 4
R321 Gear VR works with
* Samsung Galaxy S6
* Samsung Galaxy S6 Edge
R322 Gear VR works with
* Samsung Galaxy Note 5
* Samsung Galaxy S6 Edge+
* Samsung Galaxy S6
* Samsung Galaxy S6 Edge
* Samsung Galaxy S7
* Samsung Galaxy S7 Edge
R323 Gear VR works with
* Samsung Galaxy Note 5
* Samsung Galaxy S6 Edge+
* Samsung Galaxy S6
* Samsung Galaxy S6 Edge
* Samsung Galaxy S7
* Samsung Galaxy S7 Edge
* (Samsung Note 7 no longer supported)