Please be sure to send out "Certified Mail / Return Receipt Requested" as this will be your only proof of not only when you mailed it out, but when you get the "green card back" that is your proof that the IRS received it and on what date it was received by them. SO very sorry it didn't work! If it helps at all, most tax software programs out there are having serious issues with this as well.
One other possible option.....if you know the "category" of stock (S/T, L/T, etc.) you can just select a date that pushes it into the proper category as that is truly all the IRS cares about is how to tax it.
