Hi! I am using the simulated quadrotor model from the hector_quadrotor package in Gazebo. The problem is that the model can not be spawned by Gazebo, as the system seems to get stuck after showing the message "wait for the spawn service", and I have to stop the process by ctr-c. My OS is Ubuntu 12.04 precise 32bit, and the version of Gazebo is 1.5, which is integrated with the ROS Groovy. Thanks in advance for any suggestion!