Hello, I am running hectorquadrotordemo with "indoorslamgazebo.launch" launch file according to this tutorial http://www.ros.org/wiki/hector_quadrotor/Tutorials/Quadrotor%20indoor%20SLAM%20demo, it gives the following error:

*gazebo: /tmp/buildd/ros-electric-visualization-common-1.6.3/debian/ros-electric-visualization-common/opt/ros/electric/stacks/visualizationcommon/ogre/build/ogresrc_v1-7-3/OgreMain/include/OgreAxisAlignedBox.h:252: void Ogre::AxisAlignedBox::setExtents(const Ogre::Vector3&, const Ogre::Vector3&): Assertion `(min.x <= max.x && min.y <= max.y && min.z <= max.z) && "The minimum corner of the box must be less than or equal to maximum corner"' failed. ================================================================================REQUIRED process [gazebo-2] has died! process has died [pid 12268, exit code -6]. log files: /home/ling/.ros/log/a7ab0718-da89-11e1-8923-f04da2adc6ca/gazebo-2.log

Initiating shutdown!

[hectorgeotiffnode-8] killing on exit [hectortrajectoryserver-7] killing on exit [hectormapping-6] killing on exit [groundtruthtotf-5] killing on exit [robotstatepublisher-4] killing on exit [spawnrobot-3] killing on exit [gazebo-2] killing on exit Traceback (most recent call last): File "/opt/ros/electric/stacks/simulatorgazebo/gazebo/scripts/spawnmodel", line 330, in sm.callSpawnService() File "/opt/ros/electric/stacks/simulatorgazebo/gazebo/scripts/spawnmodel", line 237, in callSpawnService rospy.waitforservice('/gazebo/getphysicsproperties') File "/opt/ros/electric/stacks/roscomm/clients/rospy/src/rospy/impl/tcprosservice.py", line 156, in waitfor_service raise ROSInterruptException("rospy shutdown") rospy.exceptions.ROSInterruptException: rospy shutdown [rosout-1] killing on exit [master] killing on exit shutting down processing monitor... ... shutting down processing monitor complete done**

Can any one tell why? And how to solve this problem?