Do you have a spouse who is covered by a workplace retirement plan? If so, that and a high enough MAGI could still make you ineligible for the deduction. If filing jointly, also make sure that you have assigned to the correct spouse any Forms W-2 that you have entered.
Since you appear to be using the CD/download version of TurboTax, you can also open the IRA Contributions Worksheet and see if either of the boxes on line 10 are marked.
