Did you efile or mail your original return? I think you can only efile the Amended return if your first return was efiled and Accepted. Maybe you have to tell the program your first return was accepted.
First you need to update your return with the filing status so it knows it was filed and accepted. For the Desktop program you have to check the filing status inside the program.
Open your return and go up to menu item
File > Electronic Filing > Check Electronic Filing Status
Then save your return and close and reopen it.
