ImportError: No module named sip

edit

It was working a few months ago and I have not touched ROS since. I am using ROS electric and Ubuntu 10.04, and I am following the tutorials on how to make ROS work with Legos NXT. When I type roslaunch robot.launch I get the error:

respawning...
[nxt_ros-2] restarting process
process[nxt_ros-2]: started with pid [6573]
Traceback (most recent call last):
  File "/opt/ros/electric/stacks/nxt/nxt_ros/scripts/nxt_ros.py", line 49, in <module>
    from PyKDL import Rotation
ImportError: No module named sip
[nxt_ros-2] process has died [pid 6573, exit code 1].
log files: /home/joel/.ros/log/19cd638e-84de-11e5-a689-0026b9c3b537/nxt_ros-2*.log

I do not now what is causing this problem and am not too knowledgeable with ROS or Linux. Any help will be greatly appreciated, thank you.