@SteamTrainis correct, you must enter the amount in box 1 in box 14 under the heading of "Railroad Retirement Compensation" in order to clear the error. Try entering RR in the first column box in 14 to the right of the total compensation figure. Doing this will clear the error.
@shevon2016is also correct. There is no reason why TurboTax couldn't fix this by asking if the compensation in box 1 is Railroad compensation and then correctly proofing the Tier 1 and Tier 2 tax figures, thus preventing the error message.
