Rviz reporting no fixed frame

I'm trying to complete the [robot state publisher tutorial](http://www.romin.upm.es/wiki/index.php?title=ROS%3ATutorials/Robot_State_Publisher), but when I run: roslaunch myrobot_description myrobot_rviz.launch Rviz shows no model and in the left-hand panel reports the error "Fixed Frame [map] does not exist". myrobot.urdf.xarco: myrobot_rviz.launch: I googled that error, and other pages claim the it means there's no base_link defined in my model, but there clearly is. What am I doing wrong? Edit: I changed my launch file to: and now call it like: roslaunch myrobot_description myrobot_rviz.launch model:='$(find myrobot_description)/urdf/myrobot.urdf.xacro' and that makes the model show in Rviz, but it doesn't look any different from a the other xacrodisplay launches the tutorial goes over. Is the tutorial incomplete, or am I overlooking some steps? It says I need to have a "source that publishes the joint positions" but doesn't explain how to do that. Is that a a node I have to implement myself?