I have an atlas mp15 I bought from ebay without sound or a decoder. I bought an atlas sound decoder from a freind who installed it for me. My question is this. My model will only operate in dc mode. The lights come on, the sound works and unit does move. However, it will not work in dcc mode. I have a mrc prodigy express dcc system. Any thoughts on what the problem is. My friend tells me there should not be a problem but, his layout is dc block control. I do know that most sound decoders work on the sound only. Do I need to get an actual decorder also. My dcc system is new and works fine otherwise. Any help will be appreciated. Thanks. Ray.