I cannot tell you exactly what you must change, because as I said in my original follow-up to your question, the code you posted doesn't contain the error you're reporting. However, I believe you are seeing an error message. So the code you're running has an error. The code you posted doesn't. You didn't copy and paste your buggy code; you re-typed it here and in so doing, avoided the typo that is causing the error in the code you're running.

If you want your code to run just fine, copy what you typed here and paste it in place of your original code, because this code runs fine.