slam gmapping create a map using a bag file
I am trying to make a map using a bag file following this tutorial. However, when I run map server to save the map I receive a massage that saying "Waiting for a map" but nothing seems to be happening. There are few similar questions and answere but none of them are working in my situation. I am using Ubuntu 18.04 and ROS Melodic.
I would appreciate a little help. Thank you.