I was having the same issue as bowledw - I had made a non-deductible contribution to a Trad IRA and then converted that to my Roth IRA (also called a Backdoor Roth). I went through the steps listed by DanaB to no avail until I realized that I hadn't told TTx (or wasn't given the opportunity) that I had made a contribution to my Trad IRA that tax year. Once I navigated to that screen and completed the interview process for IRA contributions, my Trad IRA to Roth IRA conversion was then not treated as a taxable event.
