I have to ask, what are the 3 letters down in the right lower corner of your radio, by the AUX port ?
I know some 2010 Ram 3500 models had the RER radio that came with Navigation & it does work with the backup camera
I know because that is the radio that i have in my 2009 Ram 1500
also there is a software update for the RER radio
it mainly for iPhone users, Free iPhone 4 Radio Upgrade (730N RER Radio only)
read it here