Waiting on transform from /base_footprint to /map to become available before running costmap, tf error:

I want to auto navigate my P3AT. Using ROS-Fuertr (on PC1: UBUNTU 12.04 LTS) & USARSim (on PC2: windows7 ). I have my launch file move_base.launch, but when i try, $ roslaunch my_robot_name_2dnav move_base.launch i am getting an warning message, [ WARN] [1413488778.937642524]: Waiting on transform from /base_footprint to /map to become available before running costmap, tf error: [see here the full terminal output](https://www.dropbox.com/s/qgpkuoh65m3mepg/automated-issue.docx?dl=0) please help to improve this scenario.