I have a Arduino Mega and Arduino motor shield running through JMRI. I was able to program a Digitrax DZ126 decoder loco using "program on Main" function. I have a 2nd loco with a Digitrax DZ123 decoder that wont respond to Decoder Pro at all. I tested it with an old MRC throttle that isnt connected through JMRI and it programs and runs ok. I've tried with and without jumpers on 5-13 and 10-12.