tf::MessageFilter, laser callback in gmapping

edit

hi ,

i am working with offlinedata to build gridmap using gmapping in ros.

My query is why SlamGMapping::laserCallback is not getting called everytime it recieves a sensor_msgs::LaserScan.

For mycase when i am publishing 107 sensor_msgs::LaserScan and 107 /tf and 107 nav_msgs::Odometry messages SlamGMapping::laserCallback is called only for 6 times for messages 0,1,18,65,78,99.

tf::MessageFilter

  scan_filter_sub_ = new message_filters::Subscriber<sensor_msgs::LaserScan>(node_, "scan", 5);
  scan_filter_ = new tf::MessageFilter<sensor_msgs::LaserScan>(*scan_filter_sub_, tf_, odom_frame_, 5);
  scan_filter_->registerCallback(boost::bind(&SlamGMapping::laserCallback, this, _1));

SlamGMapping::laserCallback

void SlamGMapping::laserCallback(const sensor_msgs::LaserScan::ConstPtr& scan)
{
  laser_count_++;
  ROS_INFO("laser_count_= %d  sequence =%d",laser_count_,scan->header.seq);

why SlamGMapping::laserCallback is not getting called everytime it recieves sensor_msgs::LaserScan and /tf.

How to make all the scans being processed.

-- Thanks.