I think you mean the distribution code is blank on your form 1099-R. If so, you should read through the options for the code in that box and choose what is most appropriate, since that code is essential to having the distribution treated properly in TurboTax.
You will see a list of the codes on your form 1099-R, for box 7. If it helps, a normal distribution is most common, and it has a code of "7."