I am working on a multi-quadcopter simulation on gazebo.I am trying to spawn 2 quadcopter and control them in gazebo.I tried using group namespace tags to avoid topic and link overlaps .After applying group tags all the topics are published but the quadcopter remains still.I am using simple forward movement code on the quadcopter.The cmdvel topic is getting published with appropriate namespace but there is no change in the other topics(imu,groundtruth).I am working on ros indigo