Overprinted colors don't print correctly.

I've created a PDF from Quark of a document that will eventually separate into 2
spot colors. The layouts are a mix of 1) multi-ink colors spec'd in Quark and 2)
imported Illustrator EPS files that use overprinted tints.

The multi-ink colors convert to 4C process in the PDF printed from Acrobat Pro
(v7) and look fine, but no matter what I try, I cannot get the Illustrator
graphics to print simulating the overprinting.

Yes, Simulate Overprint is checked.

I've also tried other variations like converting the spot color to process (that
eliminated all overprinting in the Illustrator graphics, even in viewing),
changing the Color Profile, checking Apply Output Preview, exporting to JPG,
using the Preserve Overprint checked AND unchecked, moving the Rasters vs.
Vectors slider all the way over to 100% Rasters. All yielded the same
results--none of the Illustrator graphics printed showing the overprint that is
so obviously there onscreen.

OK, I solved my own problem with the sheer determination not to let the machine
beat me.

The problem was created by my choice in the Quark print dialogue of
"Composite CMYK" for the "Print Colors" pulldown. When I
created an new PDF using "DeviceN," the resulting PDF showed correct
separations and printed fine using the Advanced option of "Simulate
Overprinting."