The reason why I just didn't call sudoku() function is because sudoku is defined after that sonKare() function. In other words, I was thinking that I would call a function that is not defined. However, it turns out to be irrelevant in my situation because my logic goes like this:
//Something went wrong and sudoku is called
//This is the function which is called at the very beginning of everything
//Something happens and sonKare is called
I thought sonKare() won't recognize the sudoku() function, that's why I use invoke click event. As I am writing I realized that this is also a ridiculous idea
Anyway, I now just called sudoku() function and it seems like it works fine... Thank you so much...