Digital BW, The Print

Well, I finally installed my Quadtone ink cartridges in a 1280 that I 
had formerly been using for color.  (I now do my color printing on a 
2200, a nice improvement.)

When I printed out the 21step.jpg test file that MIS has linked to 
its site, the result was bad. For one thing there is no solid black 
and the black end of the 21 steps definitely does not appear to be 
getting darker at the right rate.  

I did run the nozzle cleaning procedure a few times.  

Should I run it a few more?  Is it possible that the black cartridge 
is defective?  

Any other suggestions/

Thanks in advance