# run the laserscanmatcher failed,cannot get the scan data.

I run the urg_node and demo.launch.I had run the hector mapping with urg_node successfully.But when I run the laser_scan_matcher,some errors occured:

Warning: TF_OLD_DATA ignoring data from the past for frame base_link at time 1.28284e+09 according to authority unknown_publisher

Possible reasons are listed at http://wiki.ros.org/tf/Errors%20expla... at line 273 in /tmp/binarydeb/ros-kinetic-tf2-0.5.15/src/buffer_core.cpp

...

:err: icp_loop: failed: after trimming, only 32 correspondences. :err: icp: ICP failed for some reason

   I am  very confused.I read the document according to the prompts but I still can't solve it.