VBscript problem with one element vector

I use a 3D plot VBscript component inside MathCAD 15.

This component has an input variable. When I put an array of several vectors (or matrices) as input variable all is OK (VB gets it as Variant and I can loop over its elements).

But when the input variable is an array of only one vector (or matrix) VB gets it as Double and the value of this double is -1.#QNAN. So I can't use input variable for the next calculations.

Please see attached file for reference.