The account to which you made employee contributions is not a Roth IRA but is instead a designated Roth account in a 401(k), 403(b) or 457(b). Enter amounts shown in box 12 of your W-2 only in box 12 of TurboTax's W-2 form, nowhere else in TurboTax. Go back to Deductions & Credits and remove the mistaken entry that you made there.
