Maybe I'm just being slow today, but I don't get what you mean when you say you're using the posted code to test it, which works, but you try it on the Due and it doesn't work. What are you using to test the D6T other than the Due?
If you are using a different Arduino board, remember that the Due uses a different processor and necessarily takes a different path to booting. That would impact all sorts of things. Try dropping a quarter to half second delay at the end of the setup() and see if you don't have some better results. That's the best I can do without a better understanding of what you are using that worked and didn't.
Hope it helps!
Cheers!
caltain