[uArm For ROS] ImportError: No module named msg

I’m trying to use the “uArm For ROS”, but I’m getting the following error. Does anyone know how to solve it?

$ rosrun uarm uarm_core.py connect

Traceback (most recent call last):
File “/home/mss/catkin_ws/src/UArmForROS/scripts/uarm_core.py”, line 31, in
from uarm.msg import Angles
ImportError: No module named msg

Thanks!