RTABMap Mapping and Localization

In exercise 1.1, I am able to get the 3d pointcloud map of the environment but after that when viewing the images stored in the database, I do not see the yellow and purple blobs. Also, when I proceeded on to the localization section, for exercise 1.2, when I launch the new launch file using this command:

roslaunch my_rtab_package rtab_map_localization_launch_file.launch localization:=true

and after launching rviz using:

roslaunch rtabmap_ros demo_turtlebot_rviz.launch

I am unable to get the robot to relocalize. I can’t even see any map in rviz when it loads up.

Please offer your assistance in this. Thank you.