QTR-Quadtone RIP

hi,

when printing on epson heavy weight matte paper with mis ultra 2 inks i get faint gaps in 
the light parts of the prints. this happens especially toward the end of the print-- as if the 
printer just gave up toward the end of the print...i'm using a mac, and the epson 1280. i 
just checked and i'm using the most recent version of the rip.

thank you all very much for your help.

best,

lea