Problem with instantiate() and add_child()

Godot Version

4.5

Question

Instantiate() doesn’t work ?

I’ve been using godot for a while and I’ve been doing this little bit of code a lot of times, even in my current project I’ve added this very basic method and it works. But for some reason it doesn’t work here ;

I’m trying to spawn a scene in, using this code:

func _ready():
    var child_scene : PackedScene = preload(res://scene_to_instantiate.tscn)
    var child_instance = child_scene.instantiate()
    add_child(child_instance)
    print(child_instance)

This prints <Object#null> in the console.
Where did I mess up // what should I be looking out for ?

Thanks a lot !!
PS: printing the child_scene gives the PackedScene ID, so it exists

In case someone stumble across that the problem was solved by replacing preload() with load().