QTR-Quadtone RIP

I am finally having some success (prints I like) using QTR, an Epson R2400 with K3 inks, and a calibrated mac using Snow Leopard. When I try to print from Lightroom 2.6, the QuadTone option has a strike-through line in the Print dialog, and when I try to select it it tells me that my "architecture" isn't supported." I've discovered that if I set Lightroom to open as 32-bit only, it works.

I have used the QTR 2.6.2 Snow Leopard patch. Everything works fine in other apps and when LR is set to 32-bit. Am I missing something that allows me to leave Lightroom in 64-bit?

Thanks for the help,
Jeff