TurboPrint & PrintFab

It may be a dummy questions but how do I tell turboprint to use black AND grey inks only.

If I select "grayscale photo", black and grey are being used but also color inks.
If I select "grayscale", only black ink is being used according to "Ink counters" tab.

Thanks for your help.

Since I installed from rpm, I did not see the gimp plugins proposal so File->turboprint was missing in gimp menu.

I installed plugin (in fact just linking : ln -s /usr/share/turboprint/lib/gimpplugin/gpturboprint ~/.gimp-2.6/plug-ins).

Now I have turboprint menu and it works much better.

Thanks ...

Not sure if it is a gimp problem or a turboprint but here is the issue :

I try to print a A6 picture, to do so I selected "Pagesize A6" (10.50 x 14.85cm) in turboprint Layout tab.

I checked options are correct :
> lpoptions -p hpb9180
media=A6borderless .....

Then I print my photo from gimp (file ...