Another Blu Ray hook up question

Cannot figure why i am only getting dolby digital 2 channel on standard dvd with my pioneer bdp 51fd blu ray player. I just hook it up to my older NAD T762 receiver's external outputs to use the internal dacs on the player to receive hd master & dolby true hd decoding but, now on standard dvd for some reason i am only getting dolby digital 2 channel. To receive the 5 channels of dolby digital, i had to re-connect my coax digital output and set the player back from analog to digital. Am i doing something wrong or is this what you have to do when going from a blu ray disc with hd master or dolby true hd to a standard dvd with dd or dts. My understanding was i thought the player would adjust accordly. Any help appreciated.

Make sure you are using the 7.1 analog out from the player to the reciever 7.1 input. set the player audio output to analog 7.1. switch the reciever over to 7.1 analog input should work for all material standard and blue ray
good luck