Surface Network Problems

[Paul1084]

Hi all,

I am experiencing some issues with the Create/Network in the surfaces Tab within AutoCAD 2015....

What I have is a simple aframe profile with 18 degree pitch and a short flat segment at the top instead of a point... so 3 segment Polyline aspprox 20m wide overall... very simple profile... the surface I want to create is to be 5m deep, but with a slight curve to it at the top in the z axis (creating a hump) so I copy the profile 5m in the z axis, and then add 3 line perpendicular to the profile(s) to connect them, the line at the top being an arc  (see attached pic)

I am then going to create my network surface, selecting the two profiles as my first direction, and the 2 lines & 1 arc as my second direction, and it doesn't work! I get an error:

Modeling Operation Error:
     An input section is not sufficiently smooth.
Cannot create a network surface from the selected curves.

I have re-drawn it several times, and it never works... However I have used this method plenty of times in the past with previous versions of AutoCAD, most recently probably AutoCAD 2013.... I have also tried opening an old drawing where I have one of these surfaces created using this method, and expoded, and then attempted to recreate the exact same surface, and i get the same error.... Is this a bug in AutoCAD 2015? or am I missing somthing? I have never had problems with this before, and it seems such a simple operation.

[a_tsonos2]

the solution is to  convert  pline to  spline.