Hi, I paid everything TurboTax said I owed, yet IRS saying I still owe $433.50 for "Failure to pay proper estimated tax penalty." What happened?

I paid everything I was told to pay after completing my taxes with TurboTax.  I just got a letter saying I owe $433.50 for "Failure to pay proper estimated tax penalty."  Can someone please explain what I did wrong or what TurboTax did wrong?