Houdini HDA instance issue in unity

[Conkx]

Hello there, I think my issue is an instance error but I'm not sure. I'm following this tutorial :

 and when I try to import the floor in unity it breaks everything in my scene.

Before floor import in my HDA : 

When I import it : (the wall are gone)

When I delete the HDA from the scene (not the project) and re-import it, it works until I move the curve and it came back at the state of the second screen.

here's my merge node, I tried every combinaison but still not working 

thanks a lot for any help ;'o