Atlas C420 Doppler Problem

[monon509]

I recently purchased a HO scale C420 with sound and DCC. When I run it on my
Digitrax DCC layout the button F6 witch is supposed to be the doppler shift does
not operate the doppler, instead it just gives me a read out of my locomotives
speed. That is when it is running. When it is in neutral F6 is supposed to be
start-up. Instead it gives me the read out of what address my locomotive. Even
when the locomotive is in shut down the F6 button does not start the locomotive back up. What needs to be done to fix this problem. Also as a side note, I have reset it many time, mostly due to the fact that I accidentally put the locomotive into shut down.
Thanks!