If you go into your account you can delete the onces that did not work. Hopefully, the other answers will help you get them to upload.
I had this problem once. what I had to do was open the photo in paint and save as a jpg from there. I don't know why, and I have not had the problem again.
Alice
Make sure that the picture falls within the allowed size.
Did you try making the pic a bit smaller? That was the problem I was having.