I cannot make gazebo_ros_vacuum_gripper plugin to work. Please help

Hello, I have a vacuum gripper in Gazebo simulation and I am trying to attach the gazebo_ros_vacuum_gripper plugin to make it work but without any success so far. My .xacro configuration is as follows: Gazebo/Black/robotName/${link_no}vacuum_gripper_link_${link_no}grasping200.100.01 and then to use the above, I am using the following lines in my main .xacro So with that configuration and by using rosservice call /robotName/1/on "{}" and rosservice call /robotName/1/off "{}" to activate deactivate suction, nothing happens and a target item (box) is not gripped. Any help would be greatly appreciate it! Thank you.