QTR-Quadtone RIP

Hi, I'm setting up QTR for a new Epson 7880 running PK ink,
and I'd like to create a custom profile for a glossy
paper, since all the profiles that come installed are for
MK ink/matte papers.

But when I print inkseparation.psd through the QTR print
driver as directed (selecting Quadtone RIP Calibration mode)
the paper is simply ejected from the printer and no image
is printed.

The QTR driver seems to be correctly installed, because when 
I print a ordinary test image using a MK profile, the 
image prints just fine (though of course not great looking
output.)

I must be making an obvious mistake, but I can't figure
out what it is. Does this ring a bell with anyone? I'm 
on a Mac, running through Photoshop CS4.

Thanks,
David