I had 4 rejections before I rechecked all my 1099-DIV statements carefully and found that one of them has an actual date listed for "Payment Date". I manually modified the date on form 1116 for that to the one reported on the 1099-DIV and refiled. After about 15 minutes, my federal return was accepted. I don't know if this was the actual cause, but it may work for some of you. Good luck.
Thanks to the person who made the original post and the people who replied with their own experiences. Reading them helped me to try out different tricks and kept me sane.
