Dear ros-users:

      I am learning Building a Map in Simulation in the website of http://www.ros.org/wiki/pr2_simulator/Tutorials/BuildingAMapInSimulation. When I begin to run the second step "roslaunch pr2_gazebo_wg map_building_demo.launch", it gets errors showing in the accessory. And the error happened in the last three lines in the error.txt.  What happened? Thanks in advanced!

Eileen
TJ University of Shang Hai