First some advice,,, Get one of those 3 light socket testers,, Plug it in and see if the proper lights light.
True story.. Bought a used trailer once.. the unit had a 20 amp twist lock power inlet.. The owner made his own power adapter by taking an extension cord and cutting the plug off along with a few inches of cord.. he then put a new plug on the cord hooking the white wire to the copper screw and the black wire to the silver screw.
He then put a 20 amp Twist Lock outlet on the other end of the short piece hed cut off.. Same way.. Black to silver, white to copper.
If you used his cord with his adapter. all was good.. but when I used my 100'12ga cord.. SHOCK CITY.
You see, the black wire goes to the darker color (COPPER) Screw and the white wire to the SILVER (Lighter color) Screw.
He wired both plug and socket backwards..
I had to re-wire both.