How to know if an object has been successfully gripped in gazebo with moveit

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I am working on a pick and place task and have added vacuum grippers to a ur5 robot but after turning on the grippers using the plugin and attempting to attach or grip the "wood cube 10cm" in gazebo nothing happens. I can see in the terminal that the grippers have changed to on and I currently have 9 grippers in a 3x3 attached to the ee_link and am turning them on and off using the command "rospy.ServiceProxy('/ur5/vacuum_gripper1/off', Empty)" for each of the grippers changing the number of the gripper to match each one. This does not seem to work and I cannot see any glaring faults in my configuration files etc.

I cannot seem to show the link configuration for the gripper but the plugin and joint code is below. This code is the same for each of the grippers other than the names

<joint name="gripper_joint" type="revolute">
  <axis xyz="1 0 0" />
  <parent link="tool0" />
  <child link="vacuum_gripper" />
  <origin rpy="0 1.5708 0" xyz="0.01 0.0125 0" />
  <limit effort="50" velocity="50" lower="0" upper="0" />
  <dynamics damping="0.0" friction="10"/>
</joint>
  <gazebo>
  <plugin name="gazebo_ros_vacuum_gripper" filename="libgazebo_ros_vacuum_gripper.so">
    <robotNamespace>/ur5/vacuum_gripper</robotNamespace>
    <bodyName>vacuum_gripper</bodyName>
    <topicName>grasping</topicName>
<maxForce>50</maxForce>
    <maxDistance>0.05</maxDistance>
    <minDistance>0.01</minDistance>
  </plugin>

</gazebo<>

Any help would be appreciated. thanks.