Snap! for Chrome Books does not seem to be responding to negative pitch, yaw and roll commands.

Greetings!
I would like to update my 37.18 Firmware for my CoDrone Lite to 50.18. The petrone app will not let me download it as it cannot detect my CoDrone Lite. Does Petrone work on CoDrone Lite? I am using Chrome Books, recommended by Hansol for my CoDrone Lite student program at the Science Center. The Science Center purchased 40 CoDrone Lites for our program and PD Teacher Training, On both CoDrone Lite's opened, neither respond to negative Aeronautic Commands (Yaw, Roll, Pitch etc) only positive. I tried calibration and a second Drone with the same results. Code Good.

Thank you for any guidance you can provide to resolve this issues.
sallie