QTR-Quadtone RIP

I have generated a curve that allows me to use the UT14 ink set to print on glossy papers with very good results using printer controls and gamma 2.2. I particularly like the look of Red River Ultra Pro Satin with this, so I printed a step wedge and proceeded to make an RGB-ICC that would have a more perfect ramp and presumably even better printing results. 

I scanned the printed step wedge along with a Q-13 card. I used steps 0-17 (A-B) for the calibrations step, entering the LAB value for the A, M and B steps in the calibration panel. 

Initially I created an ICC without adding the curve to. I printed a new step scale, adding the curve then printing with the new ICC. The results of this are bad, far worse than the printer controls and the curve no longer blocks the Eboni black in the deep tones so that step 21 is matte, not satin. 

I tried again, this time adding both the curve and the calibration data to the ICC creation tool. I printed another step scale using this ICC and the results are worse. The scale is clearly too dark and now steps 20 and 21 are matte. I've posted the final scan, which has all three step scales on it (it's a 16MB .tif file.) which I posted at http://sdrv.ms/UMbbdr . 

Can anyone tell me what is happening here? The more I try to improve on things, the worse they get.