I am using the desktop version of TurboTax. I have completed my return, and the TurboTax Smart Check indicates my return is completed properly and ready for submission. However, when I try to electronically submit my Federal Form 1040 to the IRS, TurboTax is giving me a message that my return cannot be transmitted, due to a missing attachment. The missing attachment relates to IRS Form 8949. Why is this occurring and what do I need to do to enable TurboTax to submit my return?