On laptops the Fn key often has to be held with the shortcut. If you run the game in windowed mode, click inside the game window first so the keyboard goes to the game.
Check that you typed testingcheats true first. It has to be entered every time the game starts — the console doesn’t remember it between sessions.
Skill and trait codes apply to the Sim selected at the bottom of the screen. Select the right Sim before entering the code.
The shift-click menu needs cheats to be enabled. Enter the command in step 2 again and try once more.
Codes can change when the game updates. Every code here carries a game version, and if it’s older than yours it’s flagged for re-checking. Tell us if you find a dead one.