I know I already read something about this topic but I didn't see an exact solution. I have Unity 2017.3.0f3 and Vuforia 6.2.10. My problem is virtual buttons. I have 64 virtual buttons(I know it's too much but a number isn't important) and they trigger well when I pressed them. But they usually trigger automatically and I have to find a solution for this. I tried to use only 3 virtual buttons, it happened again.
The floor is flat, I use a flashlight under of the phone's camera in the dark room. And camera and target in fixed position.
Thanks for all help, Have a nice day.
Adding: I have camera focus script.