PointCloud to laserscan node is not working

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I want to convert my PointCloud to laserscan and I have the following launch file:

<?xml version="1.0"?>

<launch>

<!--arg name="camera" default="camera" /-->

<!-- run pointcloud_to_laserscan node -->

<node pkg="pointcloud_to_laserscan" type="pointcloud_to_laserscan_node" name="pointcloud_to_laserscan">

  <remap from="cloud_in" to="/royale_camera_driver/point_cloud"/>
  <!--remap from="scan" to="$(arg camera)/scan"/-->
  <rosparam>
      target_frame: camera_link # Leave disabled to output scan in pointcloud frame
      transform_tolerance: 0.01
      min_height: 0.0
      max_height: 1.0

      angle_min: -1.5708 # -M_PI/2
      angle_max: 1.5708 # M_PI/2
      angle_increment: 0.0087 # M_PI/360.0
      scan_time: 0.3333
      range_min: 0.45
      range_max: 4.0
      use_inf: true
      inf_epsilon: 1.0

      # Concurrency level, affects number of pointclouds queued for processing and number of threads used
      # 0 : Detect number of cores
      # 1 : Single threaded
      # 2->inf : Parallelism level
      concurrency_level: 1
  </rosparam>

</node>

</launch>

My camera is publishing pc2 data. But this launch file seems not to work. when I type rostopic echo /scan I get no data. And I also cant display scan in rviz