I am actually surprised that your code didn’t yield a syntax error so I dug a little further. It seems that when Suz wrote the lessons, with PSP8, you had to specifically add parenthesis, commas, and spaces to appear in the SOP, but starting with version 9, it would do it for you. That is why she added the parenthesis before the “, and then she added “,” for a comma.
I have to admit I have always kept doing that myself so now, I won’t have to! See, I am even learning something new after 10+ years of scripting!