Node not found - not sure why

Godot Version

v4.3.stable.official [77dcf97d8]

Question

HEY!
So Im newish to Godot but Im pretty sure that this script should work as expected.
Im following the tutorial here: https://www.youtube.com/watch?v=LOhfqjmasi0
Everything works fine and all, no problem. The hiccup is when Ive added a new function to the game manager to reset the score.
This method is called from the killzone script itself.
When I do get the player to enter the killzone in the level, no problem, score gets reset
When I do enter the killzone of an enemy though, it gives me the following error:

E 0:00:01:0036   killzone.gd:5 @ _ready(): Node not found: "%GameManager" (relative to "/root/Game/Killzone/Enemy/Killzone").
  <C++ Error>    Method/function failed. Returning: nullptr
  <C++ Source>   scene/main/node.cpp:1792 @ get_node()
  <Stack Trace>  killzone.gd:5 @ _ready()

I thought I well understood how it works and on paper, I think it should, Im just clueless to why it doesnt work.
Included are screenshots of the game scene hierarchy, the enemy hierarchy and the killzone script

Please send help :')

Unique names only work for nodes in the same scene afaik.
i recommend to use “@export var game_manager” and then set it in the editor