Make px4fmu_v2_lpe

The system that i used is linux mint 18,when i input "make px4fmu-v2_lpe"in the terminal,it shows:

python import error: No module named ‘em’

Required python packages not installed.

On a Debian/Ubuntu system please run:

sudo apt-get install python-empy
sudo pip install catkin_pkg

but i have install these packages,when i use the system ubuntu16,i input the same command,it’s all OK!Why???