No. If there is nothing in box 12 of your W-2, that is okay. This means that none of the scenarios that this box is used for applies to you. Just enter the information you have into TurboTax exactly as it is on your W-2. Be sure to leave box 12 and any other box that is blank on your W-2, blank in TurboTax.
Additional information on what box 12 is on your W-2 can be found below.
https://ttlc.intuit.com/replies/3300234