It appears that you have mistakenly entered this as a Roth IRA contribution. A Roth 401(k) is not a Roth IRA. Enter amounts shown in box 12 of your Form 1099-R only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax. Go back to the Traditional and Roth IRA Contributions section and remove the W-2 box 12 code AA amount that you mistakenly entered there.
