I installed the people package with "sudo apt-get install ros-indigo-people" which install the people package, peoplemsgs package and others. But when I try to use the package either by printing out a topic of a message from the peoplemsgs, or do "from peoplemsgs.msg import PositionMeasurement" in my python code, both fails to find the peoplemsgs package. But when I do "source /opt/ros/indigo/setup.bash" then I can see the package. Does anyone know why?

I'm also trying to add the peoplemsgs to my workspace under /myws/src or /myws/src/mypkg/src, and modify the CMakeList.txt and package.xml, then try catkin_make which also fail because of dependency issue.