Boolean difference failure between two tetrahedrons?

I’m trying to subtract one tetrahedral-shaped closed polysurface that is inside of another large one.
It doesn’t work and I get a message saying:

“Objects do not intersect. Nothing done.”

tetrahedron-shell.3dm (57.9 KB)

The same thing happens with Rhino 5.
Can I get some help to sort this out?

From Chuck in a previous forum post:

Rhino is not currently designed to create “disjoint” hollow objects. What are you trying to accomplish?


Understood. I modelled in an escape hole & it worked.