I am trying to generating a 2D mesh on my network in the same way as in this video: https://www.youtube.com/watch?v=FazZPy9wshY

But the status is "Failed" so I can not load the mesh. I have this informations in the mesh log:

Meshing requires a height value to be specified at the following points:
(92681.54, 437611.56), etc...

With many points, these points does not correspond to any nodes or pipe but are in my 2D zone.

So I would like to understand this error