Null instance problem

Godot Version

v4.4.1

Question

Hi ! I have a problem with a transition animation i want to make. The ColorRect return to a null instance each time i try to call it. Here is a exemple of a simple print i tried to show you the problem. The ColorRect is here, child of the script as it should be. But is still not found by Godot. Why ? ( sorry if i did a stupid mistake, i'm really new to that stuff )

Look at the remote scene tree at runtime.