QTR-Quadtone RIP

I'm getting slight banding especially in the both ends on a A6 
landscape print on epson matte HW. I have tried a lot of combinations 
including increasing shadow darkness and gamma with no result. I print 
in 2800dpi as 1440dpi results in even more banding. Same image printed 
in Photoshop at the same time has absolutely no banding, so it must be 
related to the rip. On semigloss I had the same problme plus the ink 
never dries, so that's why I now go for the matte paper.
Any suggestion highly appreciated, as this RIP seems to be able to get 
rid of the colorcast produced by photoshop on the 1800.
thanks in advance,
Peter Oksen,
Denmark