Hello, I am trying to modify the multiturtlebot3 files to extend it to three turtlebots. I have successfully launched and able to control 5 bots after editing the multiturtlebot3.launch file. However when I try to run the following:

ROS_NAMESPACE=tb3_X roslaunch turtlebot3_slam turtlebot3_gmapping.launch set_base_frame:=tb3_X/base_footprint set_odom_frame:=tb3_X/odom set_map_frame:=tb3_X/map

(X is the turtlebot order from 0 to 4)

It works for 0-2. But for 3 and 4 I get the following error message.

NODES
  /tb3_4/
    turtlebot3_slam_gmapping (gmapping/slam_gmapping)

ROS_MASTER_URI=http://localhost:11311

process[tb3_4/turtlebot3_slam_gmapping-1]: started with pid [16229]
[ WARN] [1532323942.771520405, 62.618000000]: MessageFilter [target=tb3_4/odom ]: Dropped 100.00% of messages so far. Please turn the [ros.gmapping.message_notifier] rosconsole logger to DEBUG for more information.

Where should I start? I tried to set it to debug like the warning said but nothing happens. I'm using ubuntu 16.04 and kinetic if that helps.