hp 3550 black & white not printing

[genecampbell8 at yahoo.com]

First, let me say, CUPS really rocks.  I'm able to print quite reliably in color, and I'm very impressed with CUPS on my home network.

I have just one question.  I've searched this site and google without luck.  Hopefully someone here can help.

I am trying to print in black and white on my hp 355O.  I've tried both commands below and I continue to get color.  Any ideas?

lp -o saturation=0
lp -o blackplot

thanks!
Gene