Getting black scans on ground using rtabmap while generating map from point cloud [closed]

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Hello, I am using laser assembler package to convert 2D laser scans to 3D point cloud and then using the point cloud to get a 2D occupancy grid map which can be provided to move base for autonomous navigation but I am getting black scans on the ground. Also the map does not get updated in rviz when I move the robot using teleop but it gets updated in rtabmap viewer. Please can anyone tell me what could be the issue and how this can be solved ? I am using this command - rosrun rtabmap_ros rtabmap -d _subscribe_depth:=false _subscribe_rgb:=false _subscribe_scan_cloud:=true scan_cloud:=/cloud2 odom:=/odom _approx_sync:=true _queue_size:=500