problem in using PCL on ROS [closed]

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I'm trying to use PCL on ROS following this link: http:// www.ros.org/wiki/pcl/Tutorials, which just teaches me how to gain the raw 3-D image from Kinect instead of .PCD files, I did successfully compiled it, however, when I run the command:

rosrun my_pcl_tutorial example input:=/narrow_stereo_textured/points2

it didn't show anything, just like this(nothing printed on the screen so I used ctrl+C after a while):

toshiba@ubuntu:~$ rosrun my_pcl_tutorial example input:=/narrow_stereo_textured/points2
^Ctoshiba@ubuntu:~$ rosrun my_pcl_tutorial example input:=/narrow_stereo_textured/points2
^Ctoshiba@ubuntu:~$

I think maybe the topic is not "/narrow_stereo_textured/points2"(I'm using turtlebot but not PR2), so I changed the input to "/camera/depth/points" where my pointcloud2 topic really lies, but nothing changes. so anybody can help me? Thanks!