r.flexure installation

[marco97f]

Hi,
I'am writing this because I've some problems to install gflex on grassgis, I've already tried to install it using the command g.extension r.flexure and it works, but when I open the r.flexure interface and I put rasters and data, clicking on RUN it says:

MODULE IMPORT ERROR.
In order to run r.flexure or g.flexure, you must download and install
gFlex. The most recent development version is available from
https://github.com/awickert/gFlex.
Installation instructions are available on the page.
ERROR: Software dependency must be installed.

I've installed gflex also as a package in spyder (where it works fine).
Probably I missed something in the instructions...
If someone can tell me something more about it.
Thanks a lot.

Marco