The message that you are receiving is the result of you mistakenly entering $0 in box 2a of TurboTax's 1099-R form. A Form 1099-R with code 7 in box 7 and the IRA/SEP/SIMPLE box marked reporting a regular distribution must always have an amount in box 2a equal to the amount in box 1.
You can only make a QCD after you have reached age 70½. The indication that you had the custodian transfer money from an IRA to charity is made in the questions that follow the entry of the details of the Form 1099-R. TurboTax will exclude the QCD amount from the amount on Form 1040, line 4b and will include the notation "QCD" next to the line.
