Octree depth iterator

Hi all
I'm new in PCL, and I don't control C++ iterators, sorry.
Just want to access to the number of node not empty at each level of the octree.
1 8 43 220 904 etc...
The idea was to "scan" the octree at each depth.
Was expected to get the solution with depth iterator, but it doesn't work as hoped.
Does't seem to go down, just give me the number of voxel not empty at the last level:

#include <pcl/octree/octree_impl.h>
...
OctreePointCloudOccupancypcl::PointXYZ BoxTreeO(Resolution);
BoxTreeO.setInputCloud(Cloud);
BoxTreeO.defineBoundingBox(VoxelMin.x, VoxelMin.y, VoxelMin.z, VoxelMax.x, VoxelMax.y, VoxelMax.z);
BoxTreeO.addPointsFromInputCloud();

OctreePointCloudOccupancypcl::PointXYZ::Iterator j;
for (j = BoxTreeO.depth_begin(); j != BoxTreeO.depth_end(); ++j)
{
cout << "Depth:\t\t" << BoxTreeO.getTreeDepth() << endl;
cout << "LeafCount:\t\t" << BoxTreeO.getLeafCount() << endl;
}
BoxTreeO.deleteTree();
return(44);
}

What I am doing wrong, any help please?
Thanks by advance, serge

PCL 1.8.1 All-in-one
MVS 2017
Windows 10.017134

Start with pcl/octree/octree_impl.h and the OctreePointCloudOccupancy depth_begin()/depth_end() entry points used in the example. Trace how the iterator advances and how getTreeDepth() and getLeafCount() report state; done means the depth scan produces the expected non-empty node count at each level.