Lidar point cloud line trace issue

I’m trying to measure the distance between two points of a lidar point cloud.
I have a pointcloud taken by a Leica Lidar Scanner that is quite dense.
With most of the points I can trace the line from the mouse world position, but in some cases line trace returns very far locations. Is that because of little spaces among the points?
This is my blueprint:

Thank you very much.

Little update: I discovered that the points I trace are behind the pawn I use. What does this mean?