Update.
I tried to quit the Kernel, but the situation is the same.
I'm using Mathematica 11.2 if it helps.
Maybe I'm doing something wrong running the code.
I do " Evalutate Notebook" to see the output and I still get the same error.
But it's like O1, O2, ... , O5 aren't read. Since if I go in O5 and I press MAIUSC + ENTER
the plots works.