The prepost editing doesn't seem to be working. It goes to the proper screen for you to choose your edited version, but when you press "update entry" it returns an Error message, saying I cannot submit 2 pictures prior to the contest. However, obviously, I am trying to edit. I hadn't had any problems before doing so (and I have done it a bit with other photos). Is this a glich happening today?
Check if your updated image fits the site requirements - dimensions and file size. It it's close to the file size limit, try saving at a bit lower quality to get below the file size. If it still doesn't work, PM a mod to remove the first pre-post and then upload.