Flashlight in google VR game?

Hello, i am trying to develop a game using Google VR, but it seems that when i test the game in my phone, the lighting looks a little…well not the same quality when i play test on PC.
and i was trying to build a flashlight since the game is in night scene, i did not set a button for the flashlight to be turn on and off, when i test the game in PC, it looks pretty fine and able to seen most of the area in the dark.
but when i test it on my phone’s vr, i saw nothing but darkness, i dont even know the flashlight is working or not, or…is it the game has a lot of limitation/restriction when playing using phone? and the phone cant render the flashlight?
or is it something i did wrong?