Thanks for your quick reply. The problem is that after answering all the questions and then clicking the Continue button TurboTax doesn't ask me the question about whether I made nondeductible contributions to the traditional IRA; it just goes back to the "Your 1099-R Entries" screen, and when I click Continue there, takes me back to the "Your 2017 Income Summary" page.
BUT, I believe I finally figured it out. I had not seen that the IRA/SEP/Simple box was checked on the form 1099-R, and that's what triggers the questions!
Thanks again for your help.
