I have a 60441 HO GP50 Diesel with DCC (Norfolk Southern). I am new to DCC, I can not get a 4 digit addr to take, i can program a 2 digit, but not a 4 digit. using Digitrax DT400. I followed the instruction to clik the controller from ADDR-2 to ADDR-4 , however doesn't seem to change. I have changed 03 to 65, but want to change to 6556. ANy Advice?