I just received my second DCC On-Board engine (4-8-4 Niagara) to go along with aF& style diesel, also DCC On-Board. I ran both for a while, in both systems. After a time of running in DCC I decided to switch my layout to DC, ran an old DC engine with no problem but now neither of the new DCC On-Board engines will run in DC.

Any idea as to what happened. Both engines run fine in DCC but do nothing in DC