It should actually play from BOTH the stereo and multichannel analog outputs. On the receiver side, it shouldn't matter what analog input you set it to, because it is analog.
Do you have 6 cables connected from the 5.1 (multichannel) analog output of the player to the multichannel input on the receiver? Then you have to select that input on the receiver (Ext. in, or whatever it's called on your receiver). It should work, because that input is only analog on all receivers. If you only have 2 cables connected, you are not going to get surround. All the decoding is done in the player, so if you only have 2 channels connected, that is all you are going to get.