Digital BW, The Print

Helo.
I'm using the epson 890 spongeless cart with GP MIS inks. It have been 
a disaster. I spent 2oz bottes of ink and I don't have any print. 
Belive me. I don't get any good nozzle print in a month of work. I 
follow the MIS instructions and list advices, now I don't know what to 
do.....
I think that those cart are no well designed.
It is only my opinion...