Digital BW, The Print

Hello, I bought an R280 and loaded the mis 6 inkset (labeled MIS RCW).
I am comparing prints from my C88+ and the and 280 prints achieve comparable shadows and great highlights on photo rag 308 but the mid tones are really muddy. I printed a 21 step wedge with some prints and the 3 mid tones in the wedge are completely compressed into one tone. I can apply a curve in photoshop to increase contrast in the mid tones but rather not do that.  I rather understand what I am doing wrong. 

The inks are in their proper slots and the nozzle check seems to indicate that the ink cartridge order is fine.  

I am on imac G4 with photoshop cs (Old version)