Suzanne: There are two possible ways I can think of to explain
this. The first is the less likely one. It is that some light
sources are not continuous spectrum. In other word, they do not
put out all the wavelengths of light. They put out some
wavelengths of red light, some wavelenghts of blue light, etc.
This is true of florescent and flach lighting in particular,
although newer bulbs are less prone to this problem and closer
to “full spectrum” lighting.
If the pink of the CZ is not produced by a wavelength produced
by the light you use, you won’t be able to see it and will be
left with whatever other color is being shown by the light you
have. In other words, your light source doesn’t have the pink
wavelengths necessary to show the pink in the CZ, but it does
have wavelengths that show the blue that is there but usually
overpiwered by the pink.
The second possiblity is more likely. Color film has layers
sensitive to different colors. Just as the lights might not be
sensitive to all the reds (pink is a light red), the color layer
for red in the film might not be sensitive to the pink of the
CZ. However, some blue is produced by the CZ and the film is
sensitive to this. To produce the pink you would need a film
which has dyes which are sensitized differently.
I have oversimplified a little, as sometimes the color is
produced by combinations of different layers (remember yellow
paint and blue paint giving green in kindergarten, kinda like
magic??). However, the basic idea is the same. This problem
makes sense to me, as it often used to be said that violet
flowers turned blue under Ektachrome. Kodak worked on this
problem, and I guess it is much better now that ten years ago,
but I guess no one has solved the CZ problem yet.