Cloud values are not loaded

edit

My code snippet in order to build a point cloud as below:

static tf::TransformBroadcaster tfb;
tf::Transform xform;
xform.setOrigin(tf::Vector3(pose3D_LD2.pose.position.x, pose3D_LD2.pose.position.y, pose3D_LD2.pose.position.z));
xform.setRotation(tf::Quaternion(previous_poseLD_.pose.orientation.x, previous_poseLD_.pose.orientation.y, previous_poseLD_.pose.orientation.z, previous_poseLD_.pose.orientation.w));
tfb.sendTransform(tf::StampedTransform(xform, ros::Time(pose3D_LD2.header.stamp), "base_link", "laser"));
tfListener_.waitForTransform("base_link", "laser", previous_scan_.header.stamp, ros::Duration(2.0));
projector_.transformLaserScanToPointCloud("base_link", previous_scan_, cloud, tfListener_);

It neither gives error and nor emits warning messages. However, when I run "rostopic echo /cloud" it gives the following information:

header: 
  seq: 198
  stamp: 
    secs: 0
    nsecs: 0
  frame_id: cloud
points: []
channels: []
---
header: 
  seq: 199
  stamp: 
    secs: 0
    nsecs: 0
  frame_id: cloud
points: []
channels: []
---
header: 
  seq: 200
  stamp: 
    secs: 0
    nsecs: 0
  frame_id: cloud
points: []
channels: []
---
header: 
  seq: 201
  stamp: 
    secs: 0
    nsecs: 0
  frame_id: cloud
points: []
channels: []
---

It seems that the point cloud is not successfully configured. Apparently, when running the rviz, it complaints that "no messages received".

Any remedy for this weird behavior?

Thanks in advance.