hector_slam + hector_mapping + RVIZ

Hello, I need some advice or clarification of how to use hector_slam stack with rviz. I want to do the same video as we can see http://www.ros.org/wiki/hector_slam Do I am doing something wrong ? - I am using only an hokuyo - I am not using odometry or IMU ( no pitch no roll) - I used this launch file : Then I started hokuyo node and rviz but nothing appear on rviz and I still get error with /map doesnt exist Hope you can help me Thanks a lot for taking time to help or advice me.