DCS Commander can't apply power

Is there power going into the DCS Commander?

Yes. If I wire the track with just the transformer and without the commander, everything works fine. I also noticed that when I try to switch to DCS mode, the commander emits a short buzz.
Thanks

Is the power surge AC or DC, and is it connected to the appropriate input terminals?

AC. It is connected to appropriate input terminals.

Hi chefne,

Any chance you hit the DCC pass-thru?  The pass-thru disconnects the transformer input from the track output.

BTW, what AC power supply are you using?

Unfortunately, it was not in pass-thru. I use a postwar ZW. Thanks for all your suggestions.