The atlas plan can be found on train sets only web site. Everything is Bachmann. I have tried 3 different power packs. Will a reverse loop cause this because their is one. What do I need to correct the problem.

I just finished creating a train layout modeled after the  Atlas - Transbay Interwoven.  I cannot get the engine to run at all on the track. The headlights on the engine work but that is all. I have checked all connections and tryed 3 different engines. Does any one have any suggestions.