Digital BW, The Print

After recently purchasing an Epson PM G4500 printer I am now trying out
prints. The colour prints look great, but of course work needs to be done to
refine them to my preference. The question I have is that I converted a
night time image, colour, taken with a Nikon D300 from colour to B&W. On the
monitor of this macbook pro, the image is distinctly B&W but when I print
it, the grey tones are showing distinct blues with hints of purple and
perhaps green. Unfortunately the manual is in Japanese so I cannot read
through if there is a solution to this problem. Advise on what sorts of
modifications need to be made to print in B&W please. (Apologies if this is
a simple question I should be able to solve myself.)

Toodle-pip,

Allan.