Surface Gripper extension does not work on my gripper which was imported as stl file

Omniverse Isaac Sim
,
1

Isaac Sim Version

4.2.0

Operating System

Ubuntu 22.04

Topic Description

https://docs.omniverse.nvidia.com/isaacsim/latest/features/robots_simulation/ext_omni_isaac_surface_gripper.html

I try to use the surface gripper extension.

I tried to use it with omnigraph and it works great when I follow the tutorial with the two cubes.

But I fail to replicate this when I use my gripper which I imported from an .stl file

the gripper.usd has the following hierarchic:

gripper(xform)
-Visuals
--Material
-triangle(xform)
--triangle (mesh)
- --I’ve added the surface gripper here but also tried every other option like gripper(xform) or triangle (xform)

I’ve tried everything: from only using the triangle(mesh), adding rigid body and colliders preset to gripper(xform) and/or triangle(xform) and/or triangle(mesh).

How can I make it works it is so easy when I just use two cubes.
P.S. I also tried to add a cube to my gripper and just add the extension to the cube but then it doesn’t work anymore.