Digital BW, The Print

What am I doing wrong?
I'm converting raw images in Photoshop Camera Raw;
Converting them to grayscale in Photoshop CS;
Saving them as 8 bit TIFFs and passing them on to the RIP,
BUT!
The pints are coming out looking like lavender duotones
or magenta duotines, NOT grayscale.
Where am I going wrong in my workflow?
Can someone help me with the very simplest workflow to get a 
grayscale image OR the steps to save a TIFF intened for the QuadTone 
RIP.

Thanks,
Loye