I have Installed mujoco in Ubuntu 16.04 with a trial license today.But when I run the ./simulate in the directory of .mujoco/mjpro150/bin/simulate , there is nothing show on the screen. I recomplie the code in dir of mjpro150/sample and run again. I found that the function glfwInit() return false.Because these is not any error information output in the terminal, so I do not know what's problem??How can I fix this problem??