No publishing after launching pointCloudAssembler

edit

Good afternoon,

After launching this file on a ros indigo virtual machine :

<launch>
  <node type="point_cloud_assembler" pkg="laser_assembler" name="my_assembler">
    <remap from="cloud" to="/cloud"/>
    <param name="max_clouds" type="int" value="400" />
    <param name="fixed_frame" type="string" value="base_link" />
  </node>
</launch>

and calling the assemble_scans with this command :

 rosservice call /assemble_scans 100000 10000000000

I get this :

cloud: 
  header: 
    seq: 0
    stamp: 
      secs: 10
      nsecs: 0
    frame_id: base_link
  points: []
  channels: []

and no topic is published ( I expect the topic assembled_cloud to appear on rostopic list )

I have tried to change the interval of time but nothing happens.

Do you have an idea why nothing is published ?

Thank you for your time.