Boolean Operation

BU.3dm (150.6 KB)
I have 2 solids and can’t perform Boolean union or difference.
Could someone shed a bit of light on this situation,please.
Rhino 5 W10

The outer curved surfaces of the two objects are coincident, and Boolean operations frequently have problems with coincident surfaces.

Possible solutions are:

a) Alter one of the objects so the surfaces are no longer coincident. A movement of one of the surfaces a very small amount should be sufficient.

b) Use other methods such as Trim, or Split and then Delete. Then Join to recreate the solids.

Thank you david!