Wiring Lionel tubular uncoupling track for DC track power

I recently bought on eBay a complete set, the Black Cave Flyer, which used variable DC from the transformer. I have never owned a DC set of Lionel previously. I set up a loop with the O27 tubular track it came with and then some from my collection. I added an uncoupling track and wired it the way described in the instructions. When I hit the button it seems to break the circuit to the track and the uncoupler magnet does not work. It doesn;t seem like it should be complicated, what am I doing wrong? Any advice or diagrams would be useful. I already googled the matter and am now more confused from what I found there. Thanks for any assistance!

Accessories for Lionel trains are AC powered. It probably won't work with the variable DC output.

Mike