Digital BW, The Print

I just installed a CIS system on my epson 1200 and am using the MIS 
VM inkset with the Paul Roark curves. I've been testing the inks 
using the standard step wedge and have not been able to get a good 
spread of tones. I'm not gettig good highlight or shadow tones. I'm 
getting a good 100% black but my 95% drops of too quickly(should be 
the 90% tone). Same deal for the highlights. My 5% tone is too dark, 
by 5-10%. The result is that a narrow tonal range is being spread 
over 80% of the step wedge. How do i go about trying to get a better 
spread?? Where should i start? I've tried both the sRGB and ADOBE RGB
(1998) work spaces in Photoshop. The tones that i do have look great. 
Are there other or newer curves to try? I just grabbed the curves for 
the 1200 PC off the MIS site.

Off all the settings in "Color Settings" in Photoshop, which ones 
will change the way an image is printed, irrespective of the way it 
appears on the screen?

I'm printing on EAM.

Lastly, can the VM inks be used with the Piezo software?

thanx, Peter