Please check if internal test page of fiery is processed well from Fiery display. If test page gets processed but job gets drops down, your Fiery interface board is defective. I mean On fiery interface board there are two SCSI ports for print & Scan. Your Print port is bad. Only solution is to load Fiery Software V. 1.5 with SP2 ( it displays on fiery diaplay as V. 1.5 SP2) this new version actuallly swaps the port and use another port automatically for scan & Print.
I think You have a Hardware problem!
Remove the Fiery interface board and tunr on the Fiery!
Make the diagnostic.
You also can plug again the Fiery interface board!
Some times it gives a bad contact true MotherBoard.