Nec nd-3520a in 7/1 duplicator

I did put 7 burners in a duplicator but only three are burning the other four don’t(nec FW 1.04).The are all nec nd-3520a.I flashed them with fw3.05 original nec.But now only two are working.Acard ars-2032d recommended this burner as compatibel.But on top of the list stays,Please contact ACARD or distributors for writer’s Special Firmware.I receive no email back from acard.
Can somebody help me please?? :doh: