1. the nodelet rtabmap_slam/rtabmap nodelet should exist
, if there is an issue with it, post an issue
2. rtabmap_odom's odometry nodes are different processes than rtabmap_slam/rtabmap node. You may combine odometry and rtabmap nodelets inside the same node. If you want to re-use visual features already extracted by odometry node in the rtabmap node, connect rgbd_image output topic from the odometry node to rtabmap node (with the later using subscribe_rgbd:=true).