NX 8.5: Space Finder Error "Start point is on the boundary of bodies."

[handsupdb]

I'm trying to use the Space Finder command to determine the volume of the space inside an assembly. This error keeps coming up.

To remedy I've tried:
Enclosing the assembly in a thing wrapper to "seal" it - no success, I couldn't find a way to make a 0 thickness wrapper that matched the outside shape
Changing the start point (interior point) to other points - many tries no success
Creating a 0 thickness rectangular sheet inside the space and defining point on it - no success
Ensuring the point is not where two different bodies meet, or on the edge of a body defining the space - no success

Anyone encountered this error and/or know of a remedy? Judging by the error it purely has to do with the location of the interior point

 

[handsupdb]

Solved:

I removed the thin shell, and then defined my interior point a different way. I did it as a point between two points (in the empty space) and needed the two points to both be on separate bodies of the enclosing assembly.