Hi. I'm pretty new here myself. I had a similar problem. I'm thinking if you're getting sound, you're getting power, but not enough. Make sure all your track connections are properly connected and tight. Also be sure you're power wires to the track are tightly connected at both ends.

I wanted to follow up and close this issue. Originally, I had rigged up a power cord using my plug/cord from my DC track and then twisting wires to the end of the "C" shaped connectors  and inserting them into the terminals on the SCC controller. Bad idea. I ended up going to radio shack and getting a couple of female clamp type wire connectors and clamping them on the male connection point on my track. I then ran proper wire to the controller and now all is good. Appreciate the help/input.

When the DCC loco runs on DC, it makes it around the track but it slows down on the straight stretch opposite the power connection. The DC loco runs on addy "0" through the DCC controller, but there seems to be quite a bit of noise. The DC loco doesn't have sound so the nouse is just motor nouse I guess. I'm surprised the DCC controller didn't come with a connection cable. I'm thinking there just isn't enough juice getting to the track.

Only one controller connected at a time. Using addy 03 for the DCC engine. The DCC train will run with the DC controller, but I must crank up the throttle to get it moving. I'm thinking it's a power issue as the stall point is the point on the track directly opposite the power point. I'm guessing that the sound takes a lot less power than the engine. Im a bit surprised since it's only about 7' of track total. I'm rigging up a new cable to run from my DCC controller to the track later tonite to see how that works. Am trying to pry the kid away from YouTube train videos now so he can go to bed.

Ok, my son is crazy about trains.  So for Christmas, we bought him an Athearn train set with a DC locomotive. We also bought him a Bachmann DCC steam engine with tender and a digitrax controller. For Christmas morning we just set up the Athearn loop with the DC controller that came with the set. It ran perfectly. So today I am trying to get the Bachmann DCC controlled train running. It's running on the same track as the Athearn. I'm sitting here looking at the DCC controller connected to the track with the Bachmann train sitting on the track. Initially the train would run but stall at the same two points on the track loop. But now the train will not run at all. All the sound functions still work, but the train will absolutely not run. As best I could tell, the little copper strips are in contact with the tender axles. 
If ANYONE can offer suggestions, I'm all ears. My kids coming home soon and is expecting this thing to be running.