Problem with rosbag and rviz using laser scanner data

Hi guys, I’m trying to use rviz to read this laser scanner sampled data (http://classes.engineering.wustl.edu/cse550/data/Mapping1.bag) , using rosbag play. I add a display that reads the /base_scan topic and i visualize data on the grid, but in the terminal i get this error: [ WARN] [1434533618.305097862]: MessageFilter [target=map ]: Dropped 100.00% of messages so far. Please turn the [ros.rviz.message_notifier] rosconsole logger to DEBUG for more information. What does it mean and how could i solve it? Then, i’d like to use the gmapping node to read the same sample data from the /base_scan topic. When i launch the gmapping node i get this error: [ WARN] [1434533924.754354892]: MessageFilter [target=odom ]: Dropped 100.00% of messages so far. Please turn the [ros.gmapping.message_notifier] rosconsole logger to DEBUG for more information. I noticed that the gmapping node needs also to read the /ft topic to work properly, but that topic is not published when i run rosbag play Mapping1.bag, so it’s empty. Is it a problem? How can i manage it? Thank you very much, Flavio