Karamba Help

Hey guys,

for my masterproject I'm doing something strange and i really need some help.

Basically it should look like the (ugly) scetch i made here:

The hole building is made out of single rooms, connected with a vault.
Like single net construction with catenarys for the walls.

Therefore i used basically the way this guy did in the video:
https://www.youtube.com/watch?v=E4Bkeh57B88

This is the flooplan for it (yes, i should do the "Gaudi") and the red marking circles are my anchor points / supports. (I didn't do all, but i think you can imagine).

So far so good. I did already the basic file in grasshopper and karamba but i have a few problems.

It didnt work when i used concrete as a material, so i tried to set the settings from gum. But that didnt get better.

My question is: Is the material a problem for a structure like that and which one would you take? 

If it will work then, will there be catenarys or do i have to change my script? 

Thanks so much and sorry, I'm totally new in this program.