Digital BW, The Print

Hello,
I tried BO printing on my Epson 1280 and Epson Archival Matte paper. 
I chose 2880ppi (only available with glossy paper). It was a portrait 
picture. I can't see any dots but unfortunately the tonality is much 
flatter than the picture should be and, worst of all, I can see 
gradation of three densities of grays instead of smooth tonal 
transitions or the model's cheek. I couldn't find anything about such 
problems in the archives and I'd want to ask for advice on what to do 
about it. I generally like the idea of BO printing but, apart from 
more visible dots, I get better prints form my lowly Epson Color 760 
than from Epson Photo 1280. Am I making any mistake in settings or is 
this the nature of the printer?
One more difference between the printers, don't know if it means 
anything, is that when I print head allignment pattern on the Epson 
760 the printed black lines are more black than on the 1280.

Regards

Tomek