Hello all,

I met a problem when I use "rostopic echo *" on a topic which I built,
ROS complained and said "Cannot load message class for
[rviz/SelectionMessage]. Are your messages built?".  But when I wrote
a dedicated listener which subscribed to this topic, I can get the
information of the published messages to this topic.  Does anybody
know why?  By the way, "rostopic list" can list the topic and
"rostopic info" can also get the information of the topic.

Thank you!

Hao