Digital BW, The Print

OK, I have tried everything adviced to me for 2 weeks now, banding in
large black areas - night skies - are long and very faint. Print is 16
x 20 and bands are running long ways with the roll paper length. They
are faint, around 1/2 inch each, consistent bands of slightly less than
solid black. I have tried adding noise, black boost, and 2880 printing,
all on enhanced matte paper. Anybody else have a solution because so
far I love the rip and would like to use it but! Sitting here waiting,
thanks anyone. Will the newer version that jsut came out help on my
4000?