Event listener is nil

I am making a locked door system, when i tought i have finally figured everything out i got a weird error

Error connecting event listener, event listener is nil. Does anyone know how to fix this? because i dont know what is causing it to be nil.

here is a screenshot with my script error message and hierarchy.
If you need to know anything else please let me know!

Edit : I have fixed this issue, I am extremely stupid and forgot to capitalize an "i" in the function name

I forgot to capitalize an "i" in the function name