Twister does not find my custom platform

[sirde]

Hi,
I made a custom board for our electronic device. It builds ok.
I am now trying to automate tests with twister, but am getting the error:
ERROR - platform_allow in RoomzDisplay.power.sleep - unrecognized platform - RoomzDisplay/nrf5340/cpuapp

My board.yaml is basically a copy from the nrf7002dk

board.yaml:
board:
name: RoomzDisplay
vendor: ROOMZ
socs:

• name: nrf5340
  variants:
  • name: ns
    cpucluster: cpuapp
  • name: nrf7001
    cpucluster: cpuapp
    variants:
    • name: ns

Environment: nRF Connect SDK v3.1.1, Windows 10

I build using out of tree board, but I also tried to copy it "in tree", first I got the error:
ERROR: Board(s): {'RoomzDisplay'}, defined multiple times. Last defined in C:\workspace\gen3\boards\roomz\roomzdisplay\board.yml
And when I removed the --board-root argument, same unrecognized platform error.

Is there anything I have to be careful off when using a custom board?