Montero wont engage into drive?

Hi i have a 2000 mitsubishi montero sport limited 3.5L a/t my question is that after i switch from reverse to drive it wont engage unless i put it in third then back to drive the thing is the D light on the instrument panel wont turn on also the service engine soon light was on so i hooked it up to my scanner and it gave me code P0705 and said this "transmission range sensor A circuit (p/r/n/d/low input)" what does this all mean. thanks for any feedback