please help me..

when i enter the command "sudo service turtlebot start", i can see the message "turtlebot start/running, process 3198"

but!!!

when i enter the command "sudo service turtlebot start" again, i see the message "turtlebot start/running, process 4125"

i think, it's wrong.. and..

when i enter the command "rostopic list", i can see just "/rosout" and "/rosout_agg".

why i cannot see turtlebot list?

ROSMASTERURI and ROS_HOSTNAME is all right..

please help me..