Feedback Buffer Problems

Using the feedback buffer in Windows 98, I have no problem getting the rendered
z-distance of polygons on the screen using the usual feedback and selection techniques using the feedback buffer.

I’m now using Windows 2k and all of a sudden the z-distance of ALL objects in the feedback buffer is given as ZERO, and yet the z-buffer must be operating properly, as I don’t have any overlap problems!!!

I have tried this on several Win2k machines, and I get this problem on all of them, and yet on all Win98 machines there are no problems.

This is how the feedback information looks for one polygon in the array:

Number of names on stack for polygon -correct
List of all names -correct
Min z distance -wrong, allways zero
Max z distance -wrong, allways zero

Help!!!