Hi wastzzz, yeah it's related to how the csec script calculates intersections between things - if the csec rails also intersect with one another it generates another intersection point and messes up the script.

> If I detach a little the profiles, then it works, but that's not what I need..

You can still easily get what you need by using detached profiles - start with your profiles how you want them with them all touching at the ends. Select them and do a Ctrl+C to copy them to the clipboard.

Now draw in 2 lines in the side views near the ends, use Edit > Trim to cut the ends off and now you can use Csec on those cut rails that do not touch at the ends. When you are doing doing csec delete the cut up rails and do Ctrl+V to paste back in the original uncut rails and you should then have the result you want.

- Michael