VR game for iPhone

Hello everyone,

I was building a VR game for iPhone and Xcode sent me a lot of warnings but no error message. I thought it should not be a problem but I cannot play the game in the phone. When I open it there is a message that says "Place your phone into your default cardboard viewer", and nothing else can be done after this. I am using the Google cardboard SDK, Unity 5.4, and an iPhone 10.2.1. Any Help let me know,

Thanks,