== Check ros master ==
Make sure the terminal you use to start the smach viewer is connected to your ros master. To check, run:
{{{
rostopic list
}}}
and look for topics of your state machine.


== Check instrospection server ==
Your state machine needs to run an introspection server to allow the smach viewer to connect to it. A quick check is:
{{{
rostopic list | grep "smach/container_status"
}}}
If nothing is found, your state machine is not running an introspection server. See [[smach/Tutorials/Smach Viewer|this tutorial]] for more details on how to run an introspection server.