You say this is working, how do you know that it actually gets loaded:
I have doubts, what do you get when you validate:
If this Nays, could tell what’s the value of that string:
Did you forget to put a name there?
It still does not answer the question why this wouldn’t compile to start with. Did you copy / paste some nodes? This is from the vid you linked:
Can you do that? Do you see that variable on your end?