Thank you Christos,
I am still unable to get some results. It appears that I am not getting any scalar back (I used print(z_probe) to see what I got back. I am not certain why I am getting this result given that I know that the Delaunay Tessellation computed correctly (I was able to see it) and the locations that I used are within this tesselation!
I am going over everything to see what is missing!!!??
M