Why turtlebot's SLAM failed to connect kinect devices?

edit

I followed turtlebot_navigationTutorials/Build a map with SLAM.

I run

  roslaunch turtlebot_gazebo turtlebot_empty_world.launch 
  roslaunch turtlebot_navigation gmapping_demo.launch
  rosrun rviz rviz -d `rospack find turtlebot_navigation`/nav_rviz.vcg

My picture

1.Why gmapping_demo.launch show the following errors?

 [kinect_laser-5] process has died [pid 5081, exit code 255].
 log files:      /home/sam/.ros/log/a9394afe-7a3a-11e1-80c7-20cf30a23845/kinect_laser-5*.lo     g
 respawning...
 [kinect_laser_narrow-6] process has died [pid 5082, exit code 255].
 log files:      /home/sam/.ros/log/a9394afe-7a3a-11e1-80c7-20cf30a23845/kinect_laser_narro     w-6*.log
 respawning...
 [kinect_laser-5] restarting process
 process[kinect_laser-5]: started with pid [5164]
 [kinect_laser_narrow-6] restarting process
 process[kinect_laser_narrow-6]: started with pid [5165]
 [ INFO] [1333093802.058772919, 3780.477000000]: [/openni_camera] No      devices connected.... waiting for devices to be connected
 [ INFO] [1333093802.110550126, 3780.544000000]: Still waiting on map...

 [kinect_laser-5] process has died [pid 5164, exit code 255].
 log files:      /home/sam/.ros/log/a9394afe-7a3a-11e1-80c7-20cf30a23845/kinect_laser-5*.lo     g
 respawning...
 [kinect_laser_narrow-6] process has died [pid 5165, exit code 255].
 log files:      /home/sam/.ros/log/a9394afe-7a3a-11e1-80c7-20cf30a23845/kinect_laser_narro     w-6*.log
 respawning...
 [kinect_laser-5] restarting process
 process[kinect_laser-5]: started with pid [5248]
 [kinect_laser_narrow-6] restarting process
 process[kinect_laser_narrow-6]: started with pid [5249]

2.How to build a map on RViz?

Thank you~