Is It working

Dear there
It is simple problem but does not work
We have two boxes
First box from (-500,500,-300) to (500,1680,370)
Second box from (100,900,-100) to (300,1100,100)
It is required to cut box number 2 from box number 1, the result is a compound of two shells not a cavity from box 2 into box 1

Try the following commands in DRAW (I used OCCT 6.3.0):

Draw[3]> box b1 -500 500 -300 1000 2180 670
Draw[4]> box b2 100 900 -100 200 200 200
Draw[5]> av; fit
Draw[6]> bcut r b1 b2
Draw[7]> nbshapes r
Number of shapes in r
VERTEX : 16
EDGE : 24
WIRE : 12
FACE : 12
SHELL : 2
SOLID : 1
COMPSOLID : 0
COMPOUND : 1
SHAPE : 68

The point is that box 2 is completely inside box 1, therefore resulting SOLID contains two SHELL objects: one for external surface (that of box 1), and another for void space (cavity, the reversed shell of box 2). This is correct.

The problem is when i am trying to find out the void area of the solid attached it does not work
The void box has those coordinates (-500,500,-300) to (500, 1680,370)
The solid is attached

Dear Sail.

1. The result of the cut operation is quite correct.
Are you agree with that?

2. What does it mean "void area of the solid"?
Usualy an area of the solid means a value of areas of its faces.

3 "...it does not work..."
What exactly does not work?

4. "...The void box has those coordinates..."
"void box" what does it mean? Is it another major advance in science?